Rolling bearing with sensor and rotary state detecting device

ABSTRACT

A rolling bearing with sensor has an inner ring, an outer ring, rolling elements rollably disposed between the inner ring and the outer ring, a sensor provided on one of the inner ring and the outer ring and a detection member provided on the other of the inner ring and the outer ring radially opposed to the sensor which is adapted to be sensed by the sensor. A first retaining member is fixed to the outer ring end surface of the outer ring and retains one of the sensor and the detection member. A second retaining member is fixed to the inner ring end surface of the inner ring and retains the other of the sensor and the detection member. At least one of the inner end surface and the outer end surface is arranged so as to be pressed axially without the sensor or the detection member.

This is a divisional of application Ser. No. 10/496,586 filed May 24,2004, which is a National Stage entry of PCT/JP02/12007 filed on Nov.18, 2002, which claims priority from JP 2001-357696 filed on Nov. 22,2001; JP2001-396916 filed Dec. 27, 2001; JP2002-022105 filed on Jan. 30,2002; JP2002-156097 filed on May 29, 2002; and JP2002-156098 filed onMay 29, 2002. The entire disclosure of the prior application Ser. No.10/496,586 is hereby incorporated by reference.

TECHNICAL FIELD

The present invention relates to a rolling bearing with sensorcomprising a sensor of detecting the number of revolutions, etc. and arotary state detecting device.

BACKGROUND ART

Heretofore, as rolling bearings with sensor there have been thosedisclosed in JP-A-63-111416, JP-A-7-325098, JP-A-7-311212,JP-A-10-311740, etc.

The rolling bearing with sensor disclosed in JP-A-63-111416 comprises amagnetic material layer having a predetermined patterned magnetizationprovided on either one of the opposing surface of the inner ring and theouter ring and a magnetism sensor mounted on the other. The magneticmaterial layer has a plurality of patterned magnetized portions providedcircumferentially.

The rolling bearing with sensor disclosed in JP-A-7-325098 comprises amagnetized portion provided on the rotary ring and a magnetism sensorproved on the stationary ring as in the aforementioned publication andhas an increased clearance between the inner ring and the outer ring toprovide an increased space in which the magnetized portion and sensorare received.

All these structures comprise a sensor mounted on the outer ring whichis a stationary ring with a retaining member and a detection member suchas multipolar magnet mounted on the inner ring which is a rotary ring.

Further, FIG. 45 illustrates a rolling bearing 1090 with sensordisclosed in JP-A-7-311212. The rolling bearing 1090 comprises balls1093 rollably retained between an outer ring 1091 and an inner ring1092. On one axial side is provided a seal member 1094. On the endsurface opposite the seal member 1094, a sensor 1096 is provided on theouter ring 1091 with a retaining member 1095 and a detection member 1099is provided on the inner ring 1092 with a retaining member 1098.

The retaining member 1095 mounted on the outer ring 1091 has a mountingportion 1095 a fitted on the inner surface of the outer ring 1091, aflange portion 1095 b connected to the mounting portion 1095 a extendingoutward radially and a sensor retaining portion 1095 c connected to theflange portion 1095 extending axially. The flange portion 1095 b coversthe entire area of the end surface of the outer ring 1091. On the innersurface of the sensor retaining portion 1095 c is retained the sensor1096.

The retaining member 1098 mounted on the inner ring 1092 is formedhaving an L-shaped section comprising a cylindrical portion fitted onthe outer surface of the inner ring 1092 and a detection memberretaining portion extending outward radially from the cylindricalportion and retains the detection member 1099 in such an arrangementthat the detection member 1099 is axially opposed to the sensor 1096with a slight clearance therebetween.

In general, a bearing with sensor is used as a rotary state detectingdevice of detecting the speed, direction or angle of rotation of arotary body such as bearing. A rotary state detecting device comprises arotation sensor provided outside the rotary body and detection membersdisposed periodically on the surface of the rotary body. The rotationsensor calculates the speed, direction or angle of rotation of therotary body on the basis of the period of detection of the detectionmaterial and the period of disposition of the detection material.

JP-A-9-42994 discloses a slewing bearing comprising a slewing angledetector. This slewing angle detector comprises a scale and a sensoreach mounted on the inner ring and the outer ring which are bearingrings. The scale has N poles and S poles alternately arranged along thecircumference of the shaft. The sensor senses the magnetic force of Npoles and S poles to detect pulse signals and counts the number of pulsesignals. The signal converting unit converts pulse signal to angle dataaccording to the number of pulse signals and displays the angle data.

JP-A-7-218239 discloses a bearing with rotary angle detector comprisinga lattice pattern provided on the rotary ring of the bearing, aplurality of LED's provided opposed to the lattice pattern and aplurality of PD's of detecting light which has been emitted by a lightsource and modified by the aforementioned pattern. The light emitted bythe plurality of LED's each form a beam spot on the lattice pattern. Thebeam spot shows a periodical change of intensity of reflected light dueto the dark and bright portions of the lattice pattern. The plurality ofPD's each observe the change of intensity of reflected light andcalculates the rotary angle of the shaft according to the results ofobservation.

JP-A-7-218248 discloses a contact type rotary angle detecting device.This rotary angle detecting device comprises an insulating materiallayer provided on the end surface of an outer ring, a conductor patternprovided on the insulating material layer and a contactor provided on aninner ring opposed to the conductor pattern. The contactor comes incontact alternately with the conductor pattern and the insulatingmaterial with the rotation of a rotary body. The conductor pattern isshort-circuited and conducted when brought into contact with thecontactor. The rotary angle detecting device detects the rotary angle ofthe rotary body by the presence/absence of conduction of the conductorpattern to the contactor.

Further, JP-A-2000-346673 discloses a rotary speed detecting devicecomprising magnets disposed on the circumference of a rotary body and asingle magnetism sensor disposed in the vicinity of the rotary bodywhich detects the magnetic flux formed by the magnets. The rotary bodyhas a plurality of N poles, S poles and nonpolar sets provided thereinin sequence and the magnetism sensor detects the magnetic force of the Npoles, S poles and nonpolar sets to detect the rotary speed of therotary body. In addition, the magnetism sensor measures the direction ofrotation of the rotary body on the basis of the order of detection ofmagnetic poles (“N pole-S pole-nonpolar set” or “nonpolar set-S pole-Npole”) This rotary speed detecting device can measure the speed anddirection of rotation of the rotary body using a single magnetism sensorand thus doesn't need to provide another sensor therein and isadvantageous in the reduction of the size of bearing.

However, when the outer ring 1091 of a rolling bearing 1090 with sensoras shown in FIG. 45 is axially pressed with a sensor 1096 interposedtherebetween so that a load is applied thereto as shown by the arrow Pto press it into a housing, the clearance between the sensor 1096 and adetection member 1099 can be deviated, making it impossible toaccurately detect the number of revolutions or the like. Further, a loadP can be applied to set a pilot pressure for the rolling bearing 1090,occasionally causing the deviation of the clearance of the sensor 1096and the detection member 1099. The clearance between a retaining member1095 and the sensor 1096 is normally molded by a resin to fix the sensor1096 and thus can be easily damaged or deformed by a load P.

Moreover, since the clearance between the inner ring and the outer ringof a bearing is normally small, it is necessary that the sensor or theopposing detection member be formed thin. However, since the sensor isprovided integrally with a board for mounting the sensor, it isdifficult to reduce the thickness of the sensor to a predetermined limitor less. The above cited JP-A-63-111416 proposes that a magneticmaterial layer integrated to an inner ring or outer ring be provided toreduce the thickness of the detection member, but the formation of sucha layer requires a special technique that causes the increase of theproduction cost.

The above cited JP-A-7-325098 proposes that the clearance between theinner and outer rings be raised to simplify the configuration of themagnetism sensor or detection member, but a plurality of sensors must beaxially arranged in parallel, increasing the width of the entirebearing.

Further, when a rolling bearing with sensor is disposed in the vicinityof an apparatus which generates magnetic flux such as electric motor andhigh frequency power supply, magnetic flux leaked from such an apparatusaffects the circuit constituting the sensor, occasionally causingerroneous operation of the sensor. Moreover, in the case where anapparatus having its alternating power supply grounded via the housingthereof is used with the aforementioned rolling bearing with sensorattached thereto, if the housing is insufficiently grounded, the voltageof the alternating power supply is applied also to the sensor. This isaccompanied by the flow of weak current through the sensor, occasionallycausing the mixing of the output signal of the sensor with noiseattributed to the frequency of the power supply, etc.

Further, in the case of JP-A-2000-346673, for the reason of failure orreplacement of memory storing the angle before the starting of rotation,the angle data during the starting of rotation can be lost. In thiscase, it is disadvantageous in that relative reference position is lost,making it impossible to calculate absolute angle unless reference angleis reset.

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide a rolling bearing withsensor which can maintain its high precision in detection even if a loadis acted thereon so as to press against the end surface of the bearingring.

Another object of the present invention is to provide a rolling bearingwith sensor which has a plurality of sensors incorporated therein andcan be provided with a reduced width.

A further object of the present invention is to provide a rollingbearing with sensor which can block external disturbance such as leakageof magnetic flux to maintain a high precision in detection.

A further object of the present invention is to provide a bearing withsensor as a rotary state detecting device having a simple structurecapable of detecting the rotary speed, rotation direction and absoluteangle of a rotary body at the same time using a single sensor.

In order to accomplish the aforesaid objects, the rolling bearing withsensor of the present invention comprises an inner ring, an outer ring,rolling elements rollably disposed between the aforesaid inner ring andthe aforesaid outer ring, a sensor provided on one of the aforesaidinner ring and the aforesaid outer ring, a detection member provided onthe other of the aforesaid inner ring and the aforesaid outer ringradially opposed to the aforesaid sensor which is adapted to be sensedby the aforesaid sensor, a first retaining member fixed to the outerring end surface of the aforesaid outer ring which retains one of theaforesaid sensor and the aforesaid detection member and a secondretaining member fixed to the inner ring end surface of the aforesaidinner ring which retains the other of the aforesaid sensor and theaforesaid detection member, wherein at least one of the aforesaid innerend surface and the aforesaid outer end surface is arranged so as to bepressed axially without the aforesaid sensor or the aforesaid detectionmember.

Further, the rolling bearing with sensor of the present inventioncomprises an inner ring, an outer ring, rolling elements rollablydisposed between the aforesaid inner ring and the aforesaid outer ringand a plurality of sensors provided on the aforesaid inner ring andouter ring, wherein the aforesaid plurality of sensors are disposed atthe same position along the axial direction.

Moreover, the rolling bearing with sensor of the present inventioncomprises an inner ring, an outer ring, rolling elements rollablydisposed between the aforesaid inner ring and the aforesaid outer ring,a sensor provided on one of the aforesaid inner ring and outer ring, adetection member provided on the other of the aforesaid inner ring andouter ring radially opposed to the aforesaid sensor which is adapted tobe sensed by the aforesaid sensor and a noise shield disposed in thevicinity of the aforesaid sensor and the aforesaid detection member.

Further, the rotary state detecting device of the present inventioncomprises an encoder mounted on a rotary member which rotates relativeto a stationary member and formed by a plurality of magnetized regionsarranged in a line and a sensor mounted on the aforesaid stationarymember opposed to the aforesaid encoder which is adapted to detect themagnetic force of the aforesaid plurality of magnetized regions on theaforesaid encoder, wherein the aforesaid plurality of magnetized regionshave different magnetic flux densities.

Moreover, the rolling bearing with sensor of the present inventioncomprises an inner ring, an outer ring, rolling elements rollablydisposed between the aforesaid outer ring and the aforesaid inner ring,an encoder mounted on one of the aforesaid outer ring and the aforesaidinner ring and formed by a plurality of magnetized regions arranged in aline and a sensor mounted on the other of the aforesaid outer ring andthe aforesaid inner ring opposed to the aforesaid encoder which isadapted to detect the magnetic force of the aforesaid plurality ofmagnetized regions on the aforesaid encoder, wherein the aforesaidplurality of magnetized regions have different magnetic flux densities.

Further, the rotary state detecting device of the present inventioncomprises a sensor mounted on a stationary member and an encoder mountedon a rotary member which rotates relative to the stationary member andcomprising a sensor opposing surface opposing the sensor, wherein thedistance between the aforesaid sensor opposing surface of the aforesaidencoder and the aforesaid sensor changes with position and the aforesaidsensor is adapted to measure the rotary state of the rotary member bymeasuring the change of the aforesaid distance.

Moreover, the rolling bearing with sensor of the present inventioncomprises an inner ring, an outer ring, rolling elements rollablydisposed between the aforesaid outer ring and the aforesaid inner ring,a sensor mounted on one of the aforesaid outer ring and inner ring andan encoder mounted on the other of the aforesaid outer ring and innerring comprising a sensor opposing surface opposed to the aforesaidsensor, wherein the distance between the aforesaid sensor opposingsurface of the aforesaid encoder and the aforesaid sensor changes withposition and the aforesaid sensor is adapted to measure the rotary stateof the rotary member by measuring the change of the distance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a general schematic diagram of a first embodiment.

FIG. 2 is an enlarged view of an essential part of the first embodiment.

FIG. 3 is an enlarged view of an essential part of a second embodiment.

FIG. 4 is an enlarged view of an essential part of a third embodiment.

FIG. 5 is an enlarged view of an essential part of a fourth embodiment.

FIG. 6 is an enlarged view of an essential part of a fifth embodiment.

FIG. 7(a) is an enlarged view of an essential part of a sixth embodimentand FIG. 7(b) is a diagram as viewed in the direction indicated by thearrow b in FIG. 7(a).

FIG. 8 is an enlarged view of an essential part of a seventh embodiment.

FIG. 9 is an external perspective view of a multipolar magnet used inthe seventh embodiment.

FIG. 10 is an enlarged view of an essential part of an eighthembodiment.

FIG. 11 is an enlarged view of an essential part of a ninth embodiment.

FIG. 12 is an enlarged view of an essential part of a tenth embodiment.

FIG. 13 illustrates a deep groove ball bearing as a rolling devicecomprising a rotary state detecting device according to an eleventhembodiment of implementation of the present invention incorporatedtherein.

FIG. 14 is a perspective view illustrating an encoder 310.

FIG. 15 is a partly enlarged view of the encoder 310.

FIG. 16 is a graph illustrating an output signal detected by a sensor320.

FIG. 17 is a partly enlarged view of an encoder 315 used in a rotarystate detecting device according to a twelfth embodiment ofimplementation of the present invention.

FIG. 18 is a graph illustrating an output signal detected by the sensor320.

FIG. 19 illustrates a deep groove ball bearing as a rolling devicecomprising a rotary state detecting device according to a thirteenthembodiment of implementation of the present invention incorporatedtherein.

FIG. 20 is a perspective view illustrating an encoder 330.

FIG. 21 is a partly enlarged view of the encoder 330.

FIG. 22 is a partly enlarged view of an encoder 335 used in a rotarystate detecting device according to a fourteenth embodiment ofimplementation of the present invention.

FIG. 23 illustrates a deep groove ball bearing as a rolling bearing withsensor comprising a rotary state detecting device according to afifteenth embodiment of implementation of the present inventionincorporated therein.

FIG. 24 illustrates a deep groove ball bearing as a rolling devicecomprising a rotary state detecting device according to a sixteenthembodiment of implementation of the present invention incorporatedtherein.

FIG. 25 is a plan view illustrating an encoder 410.

FIG. 26 is a partly enlarged perspective view of the encoder 410.

FIG. 27 is a graph illustrating an output signal detected by a sensor420.

FIG. 28 is a partly enlarged perspective view of an encoder 415 used ina rotary state detecting device according to a seventeenth embodiment ofimplementation of the present invention.

FIG. 29 is a partly enlarged perspective view of an encoder 416 used ina rotary state detecting device according to an eighteenth embodiment ofimplementation of the present invention.

FIG. 30 illustrates an output signal detected by a sensor 425.

FIG. 31 illustrates a deep groove ball bearing as a rolling devicecomprising a rotary state detecting device according to a nineteenthembodiment of implementation of the present invention incorporatedtherein.

FIG. 32 is a plan view illustrating an encoder 430.

FIG. 33 is a partly enlarged perspective view of the encoder 430.

FIG. 34 is a partly enlarged perspective view of an encoder 435 used ina rotary state detecting device according to a twentieth embodiment ofimplementation of the present invention.

FIG. 35 is a partly enlarged perspective view of an encoder 436 used ina rotary state detecting device according to a twenty first embodimentof implementation of the present invention.

FIG. 36 is a plan view illustrating an encoder 450 in a twenty secondembodiment of implementation of the present invention.

FIG. 37 is a partly enlarged perspective view of the encoder 450.

FIG. 38 is a diagram illustrating an output signal detected by a sensor440.

FIG. 39 is a partly enlarged perspective view illustrating an encoder455 in a twenty third embodiment of implementation of the presentinvention.

FIG. 40 is a diagram illustrating an output signal detected by a sensor445.

FIG. 41 is a plan view illustrating an encoder 460 in a twenty fourthembodiment of implementation of the present invention.

FIG. 42 is a partly enlarged perspective view of the encoder 460.

FIG. 43 is a partly enlarged perspective view illustrating an encoder465 in a twenty fifth embodiment of implementation of the presentinvention.

FIG. 44 is a deep groove ball bearing as a rolling device comprising arotary state detecting device according to a twenty sixth embodiment ofimplementation of the present invention.

FIG. 45 is a schematic diagram illustrating a related art rollingbearing with sensor.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of implementation of the present invention will be describedin detail hereinafter in connection with the drawings.

First Embodiment

FIG. 1 illustrates a rolling bearing 10 with sensor of a firstembodiment of implementation of the present invention. The rollingbearing 10 with sensor comprises a plurality of balls (rolling elements)13 provided interposed between an outer ring 11 and an inner ring 12.The plurality of balls 13 are rollably retained circumferentially apartfrom each other by a retainer 13 a.

Herein, the outer ring 11 is a stationary ring and the inner ring 12 isa rotary ring.

On one axial side (left side as viewed on the drawing) of the rollingbearing 10 is provided a shield 14 as a seal member. The shield 14 isfixed to the outer ring 11 at the base end (outer periphery) thereof.The forward end (inner periphery) of the shield 14 doesn't come incontact with the inner ring 12 and is a noncontact seal member.

A contact seal member as shown in FIG. 45 can be used.

On the other axial side of the rolling bearing 10 (right side as viewedon the drawing), a first retaining member 15 is fixed to the outer ring11 and a second retaining member 18 is fixed to the inner ring 12. Thefirst retaining member 15 and second retaining member 18 may be made ofa metal and may be formed by sheet metal processing or the like.

The first retaining member 15 has a cylindrical mounting portion 15 afitted on the inner surface of the outer ring 11, a flange portion 15 bconnected to the mounting portion 15 a extending outward radially, anextension portion 15 c connected to the flange portion 15 b at the sameradial position as the mounting portion 15 a extending axially and asensor retaining portion 15 d connected to the axial end of theextension portion 15 c extending inward radially. Further, on the sideof the mounting portion 15 a opposite the flange portion 15 b (left sideas viewed on the drawing) is provided a bent portion 15 e rising inwardradially.

The second retaining member 18 has a connection portion 18 a extendingradially and caulked to a groove formed on the outer surface of theinner ring 12 at the base end thereof (inner periphery) and a detectionmember retaining portion 18 b connected to the forward end (outerperiphery) of the connection portion 18 a extending axially.

On the inner periphery of the detection member retaining portion 18 b ofthe second retaining member 18 is retained an annular multipolar magnet19 as a detection member.

The forward end of the sensor retaining portion 15 d of the firstretaining member 15 protrudes inward from the multipolar magnet 19 and asensor retaining ring 17 which is a separate body is mounted thereon. Onthe outer periphery of the sensor retaining ring 17 are retainedmagnetism sensors 16 as sensor. The magnetism sensors 16 are disposedslightly apart from each other on the inner periphery of the multipolarmagnet 19 and both the magnetism sensors are radially opposed to eachother. The first retaining member 15 doesn't come in contact with thesecond retaining member 18 and the multipolar magnet 19 and the secondretaining member 18 doesn't come in contact with the first retainingmember 15 and the magnetism sensors 16.

As the multipolar magnet 19 there is used one having a first portion 19a and a second portion 19 b having different magnetized patterns, thesecond portion 19 b being axially adjacent to the first portion 19 a.The first portion 19 a has a plurality (e.g., total of 64) of S and Npoles alternately arranged circumferentially. The second portion 19 bhas S and N poles arranged circumferentially only at one position.

The magnetism sensor 16, too, has a first portion 16 a and a secondportion 16 b which are disposed radially opposed to the first portion 19a and the second portion 19 b of the multipolar magnet 19, respectively.The rotary speed of the inner ring 12 can be observed at the firstportion 16 a of the magnetism sensor 16 and the rotary phase of theinner ring 12 can be observed at the second portion 16 b.

FIG. 2 is an enlarged view of an essential part of FIG. 1. As shown inFIG. 2, the flange portion 15 b of the first retaining member 15 is bentin the form of U having no clearance and extends radially and one of theside surfaces thereof comes in contact with the outer ring 11. Even whenany pressure load is applied to the other side surface of the flangeportion 15 b as shown by the arrow P1 in the drawing, the flange portion15 b undergoes no deformation and the pressure load P1 is transferred tothe outer ring 11 as it is because the flange portion 15 b is supportedon the end surface of the outer ring. Since the extension portion 15 cof the first retaining member 15 extends axially at the same radialposition as the mounting portion 15 a as previously mentioned, theapplication of pressure load P1 to the end surface of the outer ring viathe flange portion 15 b cannot be hindered by the extension portion 15c.

Further, in the present embodiment, substantially general area of theend surface of the inner ring 12 is positioned more inside than themagnetism sensors 16 and the sensor retaining ring 17. In other words,substantially general area of the end surface of the inner ring 12 isexposed and the applicant of pressure load can be hindered by neitherthe magnetism sensors 16 nor the sensor retaining ring 17 as shown bythe arrow P2 in the drawing.

Moreover, as shown in FIG. 2, the forward end of the bent portion 15 eprovided on the mounting portion 15 a of the first retaining member 15protrudes toward the side of the connection portion 18 a, which is aradially extending wall of the second retaining member 18, opposite theball (amount A of protrusion). Due to centrifugal force developed withthe rotation of the inner ring 12 and the second retaining member 18, alubricant such as grease present on the inner ring 12 side flows towardthe outer ring 11 along the side of the connection portion 18 a closerto the ball 13. The lubricant hits the bent portion 15 e by which it isthen guided toward the ball 13. In other words, the lubricant is checkedby the bent portion 15 e and thus doesn't leak out of the bearing space.

In accordance with the rolling bearing 10 with sensor having theaforementioned arrangement, the end surface of the inner ring can bedirectly pressed axially and the end surface of the outer ring can beaxially pressed only via the flange portion 15 b of the first retainingmember 15. Further, the multipolar magnet 19 and the magnetism sensor 16are retained radially opposed to each other. Accordingly, the positionof the multipolar magnet 19 and the magnetism sensor 16 cannot beaxially deviated during assembly, setting of pilot pressure or otheroccasions, preventing the deterioration of accuracy of detection. Sincea ball bearing has an axial clearance which is greater than radialclearance, the positional deviation of the sensor from the detectionmember can be easily raised in the related art arrangement as shown inFIG. 45, but the present embodiment has no such apprehension.

Further, in accordance with the present embodiment, the axialpositioning of the first retaining member 15 can be made by the flangeportion 15 b, making it possible to mount the first retaining member 15on the bearing accurately and easily. Moreover, since the firstretaining member 15 having the flange portion 15 b provided thereon ismounted on the outer ring 11, which is a stationary ring, with theflange portion 15 b in contact with the end surface of the outer ring 11and the magnetism sensor 16 is retained on the first retaining member15, the magnetism sensor 16 can be operated extremely accurately.

Further, the leakage of lubricant can be remarkably prevented by thebent portion 15 e provided on the first retaining member 15. Moreover,the first retaining member 15, the magnetism sensor 16 and sensorretaining ring 17, and the second retaining member 18 and multipolarmagnet 19 form a labyrinth portion by which the entrance of foreignmatters such as dust into the bearing space can be remarkably prevented.

As a sensor there may be used, e.g., temperature sensor or vibrationsensor.

Second Embodiment

FIG. 3 illustrates an enlarged view of an essential part of a rollingbearing 20 with sensor according to a second embodiment ofimplementation of the present invention. In the embodiments describedbelow, the description of members having the same configuration andaction as that of the members already described will be simplified oromitted by providing them with the same or similar reference numerals orsigns in the drawings.

In the second embodiment shown in FIG. 3, the forward end of the bentportion 15 e of the first retaining member 15 in the first embodiment isfurther provided with a seal lip 21. As shown in FIG. 3, the seal lip 21made of an elastic member such as rubber provided on the forward end ofthe bent portion 15 e comes in contact with the second retaining member18. The seal lip 21 seals the clearance between the first retainingmember 15 and the second retaining member 18.

As a sensor there may be used, e.g., temperature sensor or vibrationsensor.

Third Embodiment

FIG. 4 illustrates an enlarged view of an essential part of a rollingbearing 30 with sensor according to a third embodiment of implementationof the present invention. In the present embodiment, too, the outer ring11 is a stationary ring and the inner ring 12 is a rotary ring.

In the third embodiment shown in FIG. 4, on the first retaining member35 fixed to the outer ring 11 is retained a magnetism sensor 16 as asensor and on the second retaining member 38 fixed to the inner ring 12is retained a multipolar magnet 19 as a detection member.

The first retaining member 35 has a mounting portion 35 a fitted on theinner surface of the outer ring 11, a flange portion 35 b connected tothe mounting portion 35 a extending radially in contact with the endsurface of the outer ring, a sensor retaining portion 35 c connected tothe flange portion 35 b extending axially at the same radial position asthe mounting portion 35 a and a bent portion 35 e provided on the sideof the mounting portion 35 a opposite the flange portion 35 b. A sensorretaining ring 17 is mounted on the inner periphery of the sensorretaining portion 35 c. A magnetism sensor 16 is retained on the innerperiphery of the sensor retaining ring 17.

The second retaining member 38 has a connection portion 38 a extendingradially and caulked to a groove formed on the outer surface of theinner ring 12 at the base end thereof (inner periphery) and a detectionmember retaining portion 38 b extending axially at a radial positionmore inside than the forward end (outer periphery) of the connectionportion 38 a. The connection portion 38 a is bent in the form of Uhaving no clearance and extends radially and acts also as a seal member.On the outer periphery of the detection member retaining portion 38 b isretained a multipolar magnet 19.

As a sensor there may be used, e.g., temperature sensor or vibrationsensor.

Fourth Embodiment

FIG. 5 illustrates an enlarged view of an essential part of a rollingbearing 40 with sensor according to a fourth embodiment ofimplementation of the present invention. In the present embodiment, too,the outer ring 41 is a stationary ring and the inner ring 12 is a rotaryring.

In the fourth embodiment shown in FIG. 5, the outer ring 41 has an outerring extension portion 41 a extending axially. The end surface of theouter ring extension portion 41 a is positioned farther from the ballthan the end surface of the multipolar magnet 19 retained by the secondretaining member 18 (right side as viewed on the drawing). The firstretaining member 45 extends radially and is caulked to a groove formedon the inner surface of the outer ring extension portion 41 at the baseend thereof (outer periphery). A sensor retaining ring 17 is mounted onthe forward end of the first retaining member 45 (inner periphery). Amagnetism sensor 16 is retained on the outer periphery of the sensorretaining ring 17.

In the present embodiment, since the outer ring 41 has the outer ringextension portion 41 a, the end surface of the extension portion 41 acan be directly pressed during mounting on a housing or other occasions.

As a sensor there may be used, e.g., temperature sensor or vibrationsensor.

Fifth Embodiment

FIG. 6 illustrates a rolling bearing 110 with sensor of a fifthembodiment of implementation of the present invention. The rollingbearing 110 with sensor has a plurality of balls (rolling element) 113provided interposed between an outer ring 111 and an inner ring 112. Theplurality of balls 113 are rollably retained circumferentially apartfrom each other by a retainer 113 a.

Herein, the outer ring 111 is a stationary ring and the inner ring 112is a rotary ring.

A pair of shields 114, 115 are provided on one axial side thereof (leftside as viewed on the drawing) and on the other (right side as viewed onthe drawing) of the ball 113, respectively, as a seal structure. Theshields 114, 115 each are fixed to the outer ring 111 at the base endthereof (outer periphery). The shields 114, 115 do not come in contactwith the inner ring 112 at the forward end thereof (inner periphery) andeach are a noncontact seal member.

The shields 114, 115 prevent the leakage of lubricant enclosed in theclearance between the ball 113 and the outer ring 111 and inner ring112. Therefore, it is not necessary that the amount of lubricant to beenclosed be more than required. Further, the shields 114, 115 preventthe entrance of foreign matters such as dust into the interior of thebearing. Moreover, the shield 115 disposed on the right side as viewedon the drawing prevents the leakage of lubricant from the ball 113 sidethat causes erroneous operation of sensors 117, 118 and 119 describedlater.

The outer ring 111 has a main body 111 a which rotationally supports theball 113 and has the shields 114, 115 fixed thereto at the base endthereof and an extension portion 111 b disposed axially adjacent to themain body 111 a. Herein, the outer surface of the extension portion 111b and the outer surface of the main body 111 a are flush with each otherand the extension portion 111 b has a stepped portion 111 c formed onthe inner surface thereof as a fallen portion.

The center of the rolling element 113 is disposed at the axially centralposition C1 of the main body 111 a and the axially central position C1of the main body 111 a is offset from the axially central position C2 ofthe entire outer ring 111, including the extension portion 111 b.

To the stepped portion 111 c of the extension portion 111 b is fixed theretaining member 116 at the base end thereof.

The retaining member 116 is made of a thin sheet having a U-shapedsection. The retaining member 116 has a first sheet portion 116 a fixedto the stepped portion 111 c and a second sheet portion 116 b disposedradially apart from the first sheet portion 116 a which are connected toeach other via a connection portion 116 c. Between the first and secondsheet portions 116 a and 116 b are fixed a vibration sensor 117 and atemperature sensor 118 which are positioned in this order away from theouter ring 111 (upward as viewed on the drawing). Further, a magnetismsensor 119 is fixed to the second sheet portion 116 b on the inner ring112 side thereof with a mold resin portion 120 interposed therebetween.

The vibration sensor 117, the temperature sensor 118 and the magnetismsensor 119 are each independently electrically connected to externalcontrol circuits via an external wiring 121 disposed in the connectionportion 116 c.

The vibration sensor 117 is disposed at a position close to the outerring 111. The vibration sensor 117 is used to detect abnormal vibrationor the like of the bearing and its incidental devices by convertingvibration component given to the outer ring 111 to electrical signal andthen transferring it to the control circuit.

The temperature sensor 118 is used to prevent seizing due to lack oflubricant or the like by always detecting ambient temperature data inthe vicinity of the ball 113, the outer ring 111 and the inner ring 112and then giving it to the control circuit.

The magnetism sensor 119 is disposed opposed to and out of contact witha multipolar magnet 122 described later and is used to detect the rotaryspeed, direction of rotation and rotary phase of the inner ring 112 bygenerating a pulsed electrical signal from magnetic force generated bythe multipolar magnet 122 and then transferring it to the controlcircuit.

The vibration sensor 117, the temperature sensor 118 and the magnetismsensor 119 are disposed radially at the same position along the axialdirection of the outer ring 111 and the inner ring 112.

The inner ring 112 has a main body 112 a which rollably supports theball 113 and an extension portion 112 b disposed axially adjacent to themain body 112 a. On the outer surface of the extension portion 112 b isformed a stepped portion 112 c at the same axial position as thevibration sensor 117, the temperature sensor 118 and the magnetismsensor 119 and to the stepped portion 112 c is fixed a multipolar magnet122 which is a detection member.

The multipolar magnet 122 is formed annularly. The multipolar magnet 122has a plurality of magnetized S and N poles alternatelycircumferentially arranged on the outer surface thereof. The multipolarmagnet 122 always generates magnetic force externally, and when it isrotated with the inner ring 112, magnetic force generated by themultipolar magnet 122 is given to the magnetism sensor 119 according tothe rotary speed of the inner ring 112 so that the rotary speed of theinner ring 112 is detected.

The multipolar magnet 122, too, is disposed at the same axial positionas the vibration sensor 117, the temperature sensor 118 and themagnetism sensor 119.

In the present embodiment, since the vibration sensor 117, thetemperature sensor 118 and the magnetism sensor 119 fixed to the outerring 111 and the multipolar magnet 122 fixed to the inner ring 112 aredisposed at the same axial position in the space between the outer ring111 and the inner ring 112, the detection of resonance, etc., thedetection of ambient temperature data and the detection of the rotaryspeed of the inner ring 112 can be made without raising the width of thebearing 110.

Further, as a seal structure there may be used a contact seal member,labyrinth seal or the like. Moreover, as a rolling element there may beused a roller or tapered roller. Further, a plurality of sensors may bemounted on the inner ring or outer ring with a retaining member in suchan arrangement that it protrudes from the space between the inner ringand the outer ring.

Sixth Embodiment

FIGS. 7(a) and 7(b) each illustrate a rolling bearing 130 with sensor ofa sixth embodiment of implementation of the present invention. In theembodiments described below, the description of members having the sameconfiguration and action as that of the members already described willbe simplified or omitted by providing them with the same or similarreference numerals or signs in the drawings.

FIG. 7(b) is a diagram as viewed in the direction indicated by the arrowb in FIG. 7(a). In the present embodiment, the vibration sensor 117, thetemperature sensor 118 and the magnetism sensor 119 are disposed at aposition which is the same along the axis of the outer ring 111 butdeviated from each other along the circumference of the outer ring 111.

The present embodiment is effective even when the space between theinner ring and the outer ring is small, and the diameter of the bearingcan be reduced.

As the retaining member 116 there may be used one having a section whichis not U-shaped or one having a U-shaped section the clearance betweenthe first sheet portion 116 a and the second sheet portion 116 b ofwhich is so small that no sensors can be disposed.

Further, as a seal structure there may be used a contact seal member,labyrinth seal or the like. Moreover, as a rolling element there may beused a roller or tapered roller. Further, a plurality of sensors may bemounted on the inner ring or outer ring with a retaining member in suchan arrangement that it protrudes from the space between the inner ringand the outer ring.

Seventh Embodiment

FIG. 8 illustrates a rolling bearing 140 with sensor of a seventhembodiment of implementation of the present invention. In the presentembodiment, too, the outer ring 111 is a stationary ring and the innerring 112 is a rotary ring.

In the present embodiment, a retaining member 146 is fixed to a steppedportion 111 c in the extension portion 111 b of the outer ring 111. Theretaining member 146 has a first sheet portion 146 a fixed to thestepped portion 111 c, a second sheet portion 146 b disposed radiallyapart from the first sheet portion 146 a and a third sheet portion 146 ddisposed between the first sheet portion 146 a and the second sheetportion 146 b which are connected to each other via a connection portion146 c.

To the third sheet portion 146 d on the second sheet portion 146 b sidethereof is fixed a first magnetism sensor 149. Further, to the secondsheet portion 146 b on the third sheet portion 146 d side thereof isfixed a second magnetism sensor 150.

The first magnetism sensor 149 and the second magnetism sensor 150 aredisposed radially apart from each other. Between the first magnetismsensor 149 and the second magnetism sensor 150 is disposed as adetection member a multipolar magnet 142 radially opposed to and out ofcontact with the first magnetism sensor 149 and the second magnetismsensor 150. The multipolar magnet 142 is fixed to the inner ring 112 bythe magnet retaining member 147. The magnetic retaining member 147 isfixed to a stepped portion 112 c in the extension portion 112 b of theinner ring 112 at the base end thereof. The forward end of the magnetretaining member 147 engages with the outer surface of the multipolarmagnet 142.

As shown in FIG. 9, the multipolar magnet 142 is formed annularly. Onthe outer surface of the multipolar magnet 142 is formed a firstmagnetized portion 142 a having a plurality of S and N poles alternatelyarranged circumferentially. On the inner surface of the multipolarmagnet 142 is formed a second magnetized portion 142 b having a single Npole disposed at a predetermined position.

The magnetic force which the first magnetized portion 142 a of themultipolar magnet 142 generates externally is given to the firstmagnetism sensor 149 and the magnetic force which the second magnetizedportion 142 b of the multipolar magnet 142 generates externally is givento the second magnetism sensor 150. The first magnetism sensor 149 isused to detect the rotary speed of the inner ring 112 and the secondmagnetism sensor 150 is used to detect the phase of the inner ring 112.As the first and second magnetism sensors 149 and 150 there may be useda hall element or the like.

In the present embodiment, too, since the first magnetism sensor 149 andthe second magnetism sensor 150 fixed to the out ring 111 and themultipolar magnet 142 fixed to the inner ring 112 are disposed at thesame axial position, the detection of the rotary speed and phase of theinner ring 112 can be made without raising the width of the bearing.

Further, as a seal structure there may be used a contact seal member,labyrinth seal or the like. Moreover, as a rolling element there may beused a roller or tapered roller. Further, a plurality of sensors may bemounted on the inner ring or outer ring with a retaining member in suchan arrangement that it protrudes from the space between the inner ringand the outer ring.

Eighth Embodiment

FIG. 10 illustrates a rolling bearing 210 with sensor of an eighthembodiment of implementation of the present invention. The rollingbearing 210 with sensor comprises a plurality of balls (rollingelements) 213 provided interposed between an outer ring 211 and an innerring 212. The plurality of balls 213 are rollably retainedcircumferentially apart from each other by a retainer 214. Herein, theouter ring 211 is a stationary ring and the inner ring 212 is a rotaryring.

On one axial side of the rolling bearing 210 (left side as viewed on thedrawing) is provided a seal member 215. The seal member 215 is fixed tothe outer ring 211 at the base end thereof (outer periphery). Theforward end (inner periphery) of the seal member 215 doesn't come incontact with the inner ring 212 and the seal member 215 is a noncontactseal member. Though not shown, a contact seal member may be used.

On the other axial side of the rolling bearing 210 (right side as viewedon the drawing) is provided an interposing side wall 216 extendingradially from the inner surface of the outer ring 211 toward the innerring 212. The interposing side wall 216 is formed annularly and isfitted in a seal groove on the outer ring 211 at the outer peripherythereof. Further, to the outer ring 211 is fixed a first retainingmember 217 and to the inner ring 212 is fixed a second retaining member218.

The interposing side wall 216, the first retaining member 217 and thesecond retaining member 218 are each made of a material capable ofblocking magnetic flux such as magnetic material. As such a magneticmaterial there may be used SPCC material or a martensite or ferritestainless steel material.

The first retaining member 217 has a cylindrical mounting portion 217 afitted on the inner surface of the outer ring 211, a flange portion 217b connected to the mounting portion 217 a extending outward radiallyalong the end surface of the outer ring 211, an extension portion 217 cconnected to the flange portion 217 b extending axially at the sameradial position as the mounting portion 217 a and a side wall 217 dconnected to the axial end of the extension portion 217 c extendinginward radially. The mounting portion 217 a comes in contact with theside of the interposing side wall 216 at the forward end thereofopposite the flange portion 217 b (left side as viewed on the drawing).The interposing side wall 216 is clamped between the forward end of themounting portion 217 a and the shoulder of the seal groove on the outerring 211.

On the inner surface of the mounting portion 217 a and the extensionportion 217 c of the first retaining member 217 is retained a magnetismsensor 219 as a sensor. The magnetism sensor 219 is fixed to the firstretaining member 217 with a resin block 220 interposed therebetween. Themagnetism sensor 219 is surrounded on three sides, excluding radiallyinner side thereof, that is, on the axial side thereof closer to theball 213 by the interposing side wall 216, on the radially outer sidethereof by the mounting portion 217 a and the extension portion 217 cand on the axial side thereof opposite the ball 213 by the side wall 217d. The magnetism sensor 219 generates an electrical signal based onmagnetic flux generated by a multipolar magnet 221 described later. Theelectrical signal is transferred to a control circuit which is not shownvia an external wiring 222. The control circuit is used to amplify andregulate the waveform of the electrical signal so that it is convertedto a pulsed rotary signal by which the rotary speed of the inner ring212 is detected.

The second retaining member 218 has a cylindrical mounting portion 218 afitted on the outer surface of the inner ring 212, a flange portion 218b connected to the mounting portion 218 a extending inward radiallyalong the end surface of the inner ring 212 and an extension portion 218c connected to the flange portion 218 b extending axially at the sameradial position as the mounting portion 218 a.

On the outer surface of the mounting portion 218 a and the extensionportion 218 c of the second retaining member 218 is retained an annularmultipolar magnet 221 as a detection member.

The multipolar magnet 221 has a plurality of magnetized S and N polesalternately circumferentially arranged on the outer surface thereof. Themultipolar magnet 221 is disposed opposed to and out of contact with theradially inner side of the magnetism sensor 219 with a predeterminedclearance interposed therebetween. The multipolar magnet 221 issurrounded on two sides thereof, excluding the radially outer sidethereof and the axial side thereof closer to the ball 213, that is, onthe axial side thereof opposite the ball 213 by the side wall 217 d ofthe first retaining member 217 and on the radially inner side thereof bythe mounting portion 218 a and the extension portion 218 c. The innerdiameter of the interposing side wall 216 may be reduced (theinterposing side wall 216 may be extended toward the inner ring 212) toblock the axial side of the multipolar magnet 221 closer to the ball 213by the interposing side wall 216. The multipolar magnet 221 alwaysgenerates magnetic flux externally. The forward end of the side wall 217d of the first retaining member 217 is disposed close to but doesn'tcome in contact with the multipolar magnet 221 and the second retainingmember 218.

In this arrangement, the interposing side wall 216, the first retainingmember 217 and the second retaining member 218 form a rectangle asviewed in section and cover the magnetism sensor 219 and the multipolarmagnet 221.

The flange portion 217 b of the first retaining member 217 is bent inthe form of U having no clearance and extends radially and one of thesides thereof comes in contact with the end surface of the outer ring211. Even when a pressure load is applied to the flange portion 217 b onthe other side thereof to press the rolling bearing 210 with sensor intoa housing which is not shown, the flange portion 217 b undergoes nodeformation because it is supported by the end surface of the outer ringand the pressure load is transferred to the outer ring 211 as it is. Theflange portion 218 b of the second retaining member 218, too, has thesame action.

In accordance with the rolling bearing 210 with sensor having theaforementioned arrangement, the magnetism sensor 219 and the multipolarmagnet 221 are surrounded by the interposing side wall 216, the firstretaining member 217 and the second retaining member 218, which act asnoise shield, making it possible to block magnetic flux leaked fromdevices such as electric motor and high frequency power supply.Accordingly, the resistance to leaked magnetic flux can be enhanced toobtain a high precision in detection by the magnetism sensor 219.Further, magnetism generated by the multipolar magnet 221 can be surelycaught by the magnetism sensor 219 to obtain a high precision indetection by the magnetism sensor 219.

Further, since the interposing side wall 216 is provided on the side ofthe magnetism sensor 219 and the multipolar magnet 221 closer to theball 213, leaked magnetic flux which acts in the direction from the ball213 toward the magnetism sensor 219 and the multipolar magnet 221, too,can be blocked and the effect of the lubricant in the bearing space onthe magnetism sensor 219 can be prevented.

Moreover, by retaining the magnetism sensor 219 and the multipolarmagnet 221 by the first retaining member 217 and the second retainingmember 218 such that the magnetism sensor 219 and the multipolar magnet221 are disposed radially opposed to each other, the axial width of theentire rolling bearing 210 with sensor is reduced.

In the present embodiment, as a sensor there may be used a temperaturesensor or vibration sensor. Further, as a multipolar magnet there may beused one having a first portion and a second portion having differentmagnetization patterns, the second portion being axially adjacent to thefirst portion. The first portion may have a plurality of S and N polesalternately arranged circumferentially and the second portion may have Sand N poles arranged circumferentially only at one position. In thiscase, the magnetism sensor, too, may be arranged to have a first portionand a second portion.

Further, the magnetism sensor 219 may be provided with a transmitter andthe control circuit may be provided with a receiver so that wirelesscommunication can be made possible to omit the external wiring 222 forsignal transmission.

Ninth Embodiment

FIG. 11 is a diagram illustrating a rolling bearing 230 with sensoraccording to a ninth embodiment of implementation of the presentinvention. In the rolling bearing 230 with sensor of the presentembodiment, an interposing side wall 231 e is formed integrally with afirst retaining member 231. Other configurations are similar to that ofthe rolling bearing with sensor of the eighth embodiment. Even theconfiguration of the present embodiment can exert the same effect as theeighth embodiment.

Tenth Embodiment

FIG. 12 is a diagram illustrating a rolling bearing 240 with sensoraccording to a tenth embodiment of implementation of the presentinvention. In the rolling bearing 240 with sensor of the presentembodiment, an interposing side wall 241 e is formed integrally with afirst retaining member 241. Other configurations are similar to that ofthe rolling bearing with sensor of the eighth embodiment. Even theconfiguration of the present embodiment can exert the same effect as theeighth embodiment.

Eleventh Embodiment

An eleventh embodiment of implementation of the present invention willbe described hereinafter in detail in connection with FIGS. 13 to 16.FIG. 13 illustrates a deep groove ball bearing as a rolling devicehaving a rotation detecting device according to the eleventh embodimentof implementation of the present invention incorporated therein. Thedeep groove ball bearing has an outer ring 303, an inner ring 304, aplurality of balls 307 as rolling element, a seal ring 308 and aretainer 309.

The outer ring 303 is fixed to the inner surface 301 a of a housing 301as a stationary member. The outer ring 303 is produced by subjecting ametallic material such as carbon steel to forging or the like. The outerring 303 has an outer ring race 305 provided on the inner surfacethereof for guiding the ball 307.

The inner ring 304 is produced by subjecting a metallic material such ascarbon steel to forging or the like similarly to the outer ring 303. Theinner ring 304 is fitted on the outer surface 302 a of a shaft 302 whichis a rotary member. The inner ring 304 has an inner ring race 306provided on the outer surface thereof corresponding to the outer ringrace 305 of the outer ring 303 for guiding the ball 307. The inner ring304 rotates integrally with the shaft 302 with the rotation of the shaft302.

The balls 307 are arranged in a line between the outer ring race 305 ofthe outer ring 303 and the inner ring race 306 of the inner ring 304.The balls 307 roll over the outer ring 305 and the inner ring 306 withthe rotation of the inner ring 304 accompanying the rotation of theshaft 302.

The seal ring 308 blocks and seals both the two openings of the spacereceiving the balls 307 between the outer ring 303 and the inner ring304. The seal ring 308 prevents the entrance of dust, water content,foreign matters, etc. into the space receiving the balls and the leakageof lubricant from the space receiving the balls. The seal ring 308 isfixed at a fixing portion 303 b formed on the inner surface of the outerring 303.

The retainer 309 retains the balls 307 rollably between the outer ringrace 305 and the inner ring race 306. As the retainer 309 there may beused a pressed cage, a machined cage, or the like.

On the outer surface 302 a of the shaft 302 is provided standing anannular encoder retaining member 311. The encoder retaining member 311extends from the outer surface 302 a of the shaft 302 toward the housing301, i.e., outward radially from the shaft 302. On the axial side of theencoder retaining member 311 is provided an encoder 310 facing axially.

On the other hand, on the inner surface 301 a of the housing 301 isprovided standing a sensor retaining member 321. The sensor retainingmember 321 extends from the inner surface 301 a of the housing 301toward the shaft 302, i.e., inward radially from the housing 301. On theaxial side of the sensor retaining member 321 is provided a singlesensor 320. The sensor 320 is disposed axially opposed to the encoder310.

FIG. 14 is a perspective view illustrating the encoder 310 and FIG. 15is a partly enlarged view of FIG. 14. The encoder 310 has an annularshape having a greater width in the radial direction than in the axialdirection. The encoder 310 is formed having a plurality of N poles 312and S poles 313 alternately arranged annularly at an equal interval. Theplurality of N poles 312 and S poles 313 are magnetized regions havingdifferent magnetic flux densities.

The magnetized regions constituting the encoder 310 each have areference magnetized region having a certain minimum magnetic fluxdensity. Further, the various magnetized regions each are given magneticflux densities which increase from magnetized region to next magnetizedregion clockwise as viewed from the sensor 320 with the referencemagnetized region as reference. In some detail, in the presentembodiment, the various magnetized regions each are given magnetic fluxdensities.A(k)=k·Aref  (Equation 1)

-   -   A(k): Magnetic flux density of magnetized region k-th next        clockwise to the reference magnetized region    -   Aref: Magnetic flux density of the reference magnetized region

In other words, the magnetic flux density of the magnetized region k-thnext to the reference magnetized region is k times that of the referencemagnetized region. Next to the magnetized region having a maximummagnetic flux region is disposed the reference magnetized region havinga minimum magnetic flux density.

As the material of the encoder there may be used an alnico magnet,ferrite magnet, samarium-cobalt magnet, neodymium-iron-boron magnet orbonded magnet obtained by mixing various magnet powders with a plasticor the like, molding the mixture and solidifying the molded material.Since the magnetic flux density of the various magnetized regions needto be different, the bonded magnet, which can easily be designed to haveany magnetic flux density, is preferably used. Herein, a bonded magnetmade of a ferrite powder-containing plastic is used. The magnetic forceof a magnet changes with temperature. Therefore, it is necessary thatthe magnetization intensity be determined such that the peak of amagnetized region is not the same as that of another under the workingtemperature conditions.

The N pole 312 and S pole 313 thus arranged each form therearound amagnetic field having an intensity corresponding to the polarity andmagnetic flux density thereof. Accordingly, a magnetic fieldcorresponding to the intensity of magnetic flux density of N pole 312and S pole 313 is formed around the encoder 310. The position(disposition angle) of the reference magnetized region of the encoder310 is stored as a reference of the absolute angle of the shaft in acontrol circuit which is not shown.

The sensor 320 is a magnetism sensor which detects the magnetic fieldformed by the encoder 310. The sensor 320 is disposed close to thesurface of the encoder 310 and is capable of sensing the magnetic fieldformed by the various magnetized regions. As the sensor 320 there may beused one capable of detecting magnetic field such a shall element andcoil. Herein, description will made with reference to the case where ahall element is used by way of example. A hall element is an elementwhich generates electric current according to the intensity anddirection of magnetic flux crossing the hall element.

The encoder 310 rotates with the rotation of the shaft 302. The sensor320 outputs electric current value according to the intensity anddirection of magnetic flux formed by N pole 312 and S pole 313positioned opposed to the sensor 320 to a control circuit which is notshown via a cable 322.

FIG. 16 is a graph illustrating the output signal detected by the sensor320. In FIG. 16, the ordinate indicates the intensity of output signaland the abscissa indicates time. The magnitude of the output signal isproportional to the intensity of magnetic flux and the sign of outputsignal is determined by the direction of magnetic flux. Herein, thepulse which appears on the leftmost in FIG. 16 is a pulse generated bythe magnetic flux formed by the reference magnetized region. FIG. 16shows that the absolute value of the intensity of pulse peak increaseswith time. Accordingly, in the case of FIG. 16, the control circuitjudges that the shaft 302 rotates in the direction of increase of theintensity of N pole 312 or S pole 313, i.e., counterclockwise as viewedfrom the sensor 320. Then, the control circuit counts the number ofpeaks detected per unit time and calculates the rotary speed on thebasis of the counted number of peaks and the interval at which themagnetized regions are disposed.

Further, the control circuit determines the absolute angle of the shafton the basis of the peak intensity. In the case where the peak (point Aor C in FIG. 16) of the sensor is detected, the control circuit judgesthat the magnetized region corresponding to the output thus detected isdisposed opposed to the sensor 320. Then, the control circuit judgesthat the shaft is positioned at the absolute angle corresponding to themagnetized region thus detected. Alternatively, in the case where theoutput of the sensor is the value at point B in between the peaks, theabsolute angle of point B is calculated from the ratio of intensity atpoint A, which is the immediately previous peak, to the differencebetween the intensity at point A and at point B. In some detail, theangle at point B is calculated by the following equation.θ(B)=θ(A)+180b/a·n  (Equation 2)

-   -   θ(A): Absolute angle at point A    -   θ(B): Absolute angle at point B    -   a: Output intensity at point A    -   b: Difference between output intensity at point A and at point B    -   n: Total number of magnetized regions disposed on encoder

As mentioned above, in accordance with the present embodiment, theencoder 310 and the sensor 320 are disposed axially opposed to eachother. Further, the encoder 310 is formed by a plurality of N poles 312and S poles 313 arranged such that the magnetic flux density graduallyincreases. Accordingly, the single sensor 320 can be used to detect thespeed, direction and angle of rotation of the shaft 302 at the sametime.

Accordingly, the speed, direction and angle of rotation of the shaft canbe detected by a simple structure, making it possible to reduce thenumber of parts and hence the part cost. Further, the reduction of thenumber of parts improves assemblability, making it possible to reducethe assembly cost as well.

Further, since only one sensor is required, the space in the bearing canbe saved, making more compact design possible as a whole. Moreover, thereduction of the number of sensors leads to the reduction of the weightof the bearing as well, contributing to the reduction of fuelconsumption if the bearing is used for automobile or the like.

While the present embodiment has been described with reference to thecase where the magnetic flux density of the magnetized regions graduallyincreases, a plurality of magnetized region groups the magnetized fluxdensity of which gradually increases may be prepared and arranged in aline. In this case, by counting the number of times by which themagnetic flux of the reference magnetized region contained in therespective magnetized region group is detected, the absolute angle ofmagnetic flux can be unequivocally determined.

Further, the plurality of magnetized region groups may be arranged suchthat only the intensity of the reference magnetized regions are madedifferent. In this case, the absolute angle can be determined with theintensity of the reference magnetized region which has just beendetected as reference.

Even when the magnetized regions are arranged such that the magneticflux density gradually decreases, the same effect can be exerted.

Twelfth Embodiment

A twelfth embodiment of implementation of the present invention will bedescribed hereinafter in connection with FIGS. 17 and 18. Herein, thesame members as mentioned in the eleventh embodiment will be given thesame reference numerals and signs and their description will be omitted.

FIG. 17 is a partly enlarged view of an encoder 315 used in a rotationdetection device according to the twelfth embodiment of implementationof the present invention. In the present embodiment, the encoder 315 isdisposed opposed to a sensor 320 similar to the encoder 310.

The encoder 315 has an annular shape having a predetermined axial width.The sensor-opposing surface of the encoder 315 is formed by arranging aplurality of N poles 316 annularly at an equal interval. The pluralityof N poles 316 are magnetized regions having different magnetic fluxdensities. A back side of the sensor-opposing surface is magnetized by Spole.

The magnetized regions constituting the encoder 315 have a referencemagnetized region having a minimum magnetic flux density. The variousmagnetized regions each are given magnetic flux densities which increasefrom magnetized region to next magnetized region clockwise as viewedfrom the sensor 320 with the reference magnetized region as reference.In some detail, in the present embodiment, the various magnetizedregions each are given magnetic flux densities according to Equation 1as in the eleventh embodiment.

Thus, N poles 316 thus arranged form therearound a magnetic field havingan intensity corresponding to the respective polarity and magnetic fluxdensity. Accordingly, a magnetic field corresponding to the intensity ofmagnetic flux density of N pole is formed around the encoder 315. Theposition (disposition angle) of the reference magnetized region of theencoder 315 is stored in a control circuit which is not shown as areference of the absolute angle of the shaft.

The encoder 315 rotates with the rotation of the shaft 302. The sensor320 outputs electric current value according to the intensity anddirection of magnetic flux formed by N pole 316 positioned opposed tothe sensor 320 to a control circuit which is not shown via a cable 322.

FIG. 18 is a graph illustrating the output signal detected by the sensor320. In FIG. 18, the ordinate indicates the intensity of output signaland the abscissa indicates time. The magnitude of the output signal isproportional to the intensity of magnetic flux and the sign of outputsignal is determined by the direction of magnetic flux. Herein, thepulse which appears on the leftmost in FIG. 18 is a pulse generated bythe magnetic flux formed by the reference magnetized region. FIG. 18shows that the intensity of pulse peak increases stepwise with time.Accordingly, in the case of FIG. 18, the control circuit judges that theshaft 302 rotates in the direction of increase of the intensity of Npole 316, i.e., counterclockwise as viewed from the sensor 320. Then,the control circuit counts the number of peaks detected per unit timeand calculates the rotary speed on the basis of the counted number ofpeaks and the interval at which the magnetized regions are disposed.

Further, the control circuit determines the absolute angle of the shafton the basis of the intensity of pulse peak. In the present embodiment,the output pulse of the sensor 320 has a flat gentle peak. Accordingly,the angle resolution is deteriorated as compared with the eleventhembodiment. The control circuit has a threshold value corresponding tothe disposition angle of the various magnetized regions. Further, whenthe control circuit detects that the value detected exceeds thethreshold value, it is judged that the encoder passes by thecorresponding angle.

As mentioned above, in accordance with the present embodiment, theencoder 315 and the sensor 320 are disposed axially opposed to eachother. Further, the sensor-opposing surface of the encoder 315 is formedby a plurality of N poles arranged such that the magnetic flux densitygradually increases. Accordingly, the single sensor 320 can be used todetect the speed, direction and angle of rotation of the shaft 302 atthe same time, making it possible to exert the same effect as in theeleventh embodiment.

In the present embodiment, since the sensor-opposing surface of theencoder is formed by only N poles the magnetic flux density of whichgradually increase, the peak value thus detected is flat. Accordingly,as compared with the case where there is only one peak value, thepercent occurrence of peak detection error is reduced, making itpossible to detect peak with a higher reliability.

While the present embodiment has been described with reference to thecase where the sensor-opposing surface of the encoder is formed by Npoles, the sensor-opposing surface of the encoder may be formed by Spoles. In this case, the detection of rotary speed, direction ofrotation and absolute angle is made in the same manner as in the presentembodiment except that the sign of output signal is inverted.

Thirteenth Embodiment

A thirteenth embodiment of implementation of the present invention willbe described in detail in connection with FIGS. 19 and 20. Herein, thesame members as mentioned in the eleventh or twelfth embodiment will begiven the same reference numerals and signs and their description willbe omitted.

FIG. 19 illustrates a deep groove ball bearing as a bearing with sensorhaving a rotation detecting device according to the thirteenthembodiment of implementation of the present invention incorporatedtherein. The deep groove ball bearing has an outer ring 303, an innerring 304, a plurality of balls 307 as rolling element, a seal ring 308and a retainer 309.

In the present embodiment, the seal ring 308 blocks and seals one ofboth-end openings of the space receiving the balls 307 between the outerring 303 and the inner ring 304. The other of both-end openings of thespace receiving the balls 307 is blocked and sealed by an encoderretaining member 331 and a sensor retaining member 341.

The sensor retaining member 341 is an annular member having a C-shapedsection with two parallel ends. The sensor retaining member 341 is fixedto the axial end 303 c of the outer ring 303 and protrudes axially fromthe outer ring 303. On the radially inner side of the sensor retainingmember 341 is disposed a sensor 340 facing radially.

The encoder retaining member 331 is an annular member having a L-shapedsection. The encoder retaining member 331 is fixed to the axial end 304b of the inner ring 304 and protrudes axially from the inner ring 304.The forward end of the sensor retaining member 341 is disposed betweenboth the two ends of the sensor retaining member 341. The encoderretaining member 331 and the sensor retaining member 341 play the samerole as the seal ring 308 in cooperation with each other. On the radialside of the encoder retaining member 331 is disposed an encoder 330. Theencoder 330 is disposed radially opposed to the sensor 340.

FIG. 20 is a perspective view illustrating the encoder 330 and FIG. 21is a partly enlarged view of FIG. 20. The encoder 330 has an annularshape having a greater width in the axial direction than in the radialdirection. The encoder 330 is formed having a plurality of N poles 332and S poles 333 alternately arranged annularly at an equal interval. Theplurality of N poles 332 and S poles 333 are magnetized regions havingdifferent magnetic flex densities.

The magnetized regions constituting the encoder 330 each have areference magnetized region having a certain minimum magnetic fluxdensity. Further, the various magnetized regions each are given magneticflux densities which increase from magnetized region to next magnetizedregion clockwise as viewed from the ball 307 with the referencemagnetized region as reference. The magnetic flux density of the variousmagnetized regions in the present embodiment is as represented byEquation 1 as mentioned above.

The N pole 332 and S pole 333 thus arranged each form therearound amagnetic field having an intensity corresponding to the polarity andmagnetic flux density thereof. Accordingly, a magnetic fieldcorresponding to the intensity of magnetic flux density of N pole 332and S pole 333 is formed around the encoder 330. The position(disposition angle) of the reference magnetized region of the encoder330 is stored as a reference of the absolute angle of the shaft in acontrol circuit which is not shown.

The sensor 340 is a magnetism sensor which detects the magnetic fieldformed by the encoder 330. The sensor 340 is disposed close to thesurface of the encoder 330 and is capable of sensing the magnetic fieldformed by the various magnetized regions. As the sensor 340 there may beused one similar to the sensor 320 of the eleventh embodiment.

The encoder 330 rotates with the rotation of the shaft 302. The sensor340 outputs electric current value according to the intensity anddirection of magnetic flux formed by N pole 332 and S pole 333positioned opposed to the sensor 340 to a control circuit which is notshown via a cable 322.

The output signal detected by the sensor 320 is similar to that shown inFIG. 16. As in the eleventh embodiment, the magnitude of the outputsignal is proportional to the intensity of magnetic flux and the sign ofoutput signal is determined by the direction of magnetic flux.

In this case, the control circuit judges that the shaft 302 rotates inthe direction of increase of the intensity of N pole 332 or S pole 333,i.e., counterclockwise as viewed from the ball 307. Then, the controlcircuit counts the number of peaks detected per unit time and calculatesthe rotary speed on the basis of the counted number of peaks and theinterval at which the magnetized regions are disposed.

Further, the control circuit determines the absolute angle of the shafton the basis of the peak intensity. In the case where the peak (point Aor C in FIG. 16) of the output of the sensor is detected, the controlcircuit judges that the magnetized region corresponding to the outputthus detected is disposed opposed to the sensor 340. Then, the controlcircuit judges that the shaft is positioned at the absolute anglecorresponding to the magnetized region thus detected.

Alternatively, in the case where the output of the sensor is the valueat point B in between the peaks, the absolute angle of point B iscalculated from the ratio of intensity at point A, which is theimmediately previous peak, to the difference between the intensity atpoint A and at point B. In some detail, the angle at point B iscalculated by Equation 2.

As mentioned above, in accordance with the present embodiment, theencoder 330 and the sensor 340 are disposed radially opposed to eachother. Further, the encoder 330 is formed by a plurality of N poles 332and S poles 333 arranged such that the magnetic flux density graduallyincreases. Accordingly, the single sensor 340 can be used to detect thespeed, direction and angle of rotation of the shaft 302 at the sametime, making it possible to exert the same effect as in the eleventhembodiment.

Further, in the present embodiment, since the outer ring 303 and innerring 304 of the bearing, the encoder 330 and the sensor 340 are formedintegrally, assembly can be completed merely by disposing the bearingbetween the shaft and the housing if the encoder and the sensor havebeen previously mounted on the bearing. Accordingly, the efficiency inassembly can be enhanced, contributing to the reduction of assemblycost.

Moreover, the same rotation detecting device as in the presentembodiment can be applied to the bearing with sensor described in any ofthe first to tenth embodiments.

Fourteenth Embodiment

A twelfth embodiment of implementation of the present invention will bedescribed hereinafter in connection with FIG. 22. Herein, the samemembers as mentioned in the eleventh to thirteenth embodiments will begiven the same reference numerals and signs and their description willbe omitted.

FIG. 22 is a partly enlarged view of an encoder 335 used in a bearingwith sensor having a rotation detecting device according to thefourteenth embodiment of implementation of the present inventionincorporated therein. In the present embodiment, the encoder 335 isdisposed opposed to a sensor 340 similarly to the encoder 330.

The encoder 335 has an annular shape having a predetermined axial width.The sensor-opposing surface of the encoder 335 is formed by arranging aplurality of N poles 336 annularly at an equal interval. The pluralityof N poles 336 are magnetized regions having different magnetic fluxdensities. The encoder 335 is magnetized by S pole on the side thereofopposite the sensor.

The magnetized regions constituting the encoder 335 have a referencemagnetized region having a minimum magnetic flux density. The variousmagnetized regions each are given magnetic flux densities which increasefrom magnetized region to next magnetized region clockwise as viewedfrom the ball 307 with the reference magnetized region as reference. Insome detail, in the present embodiment, the various magnetized regionseach are given magnetic flux densities according to Equation 1 as in theeleventh to thirteenth embodiments.

Thus, N poles 336 thus arranged form therearound a magnetic field havingan intensity corresponding to the respective polarity and magnetic fluxdensity. Accordingly, a magnetic field corresponding to the intensity ofmagnetic flux density of N pole is formed around the encoder 335. Theposition (disposition angle) of the reference magnetized region of theencoder 335 is stored in a control circuit which is not shown as areference of the absolute angle of the shaft.

The encoder 335 rotates with the rotation of the shaft 302. The sensor340 outputs electric current value according to the intensity anddirection of magnetic flux formed by N pole 336 positioned opposed tothe sensor 340 to a control circuit which is not shown via a cable 322.

The output signal detected by the sensor 340 is similar to that shown inFIG. 18. In FIG. 18, the ordinate indicates the intensity of outputsignal and the abscissa indicates time. The magnitude of the outputsignal is proportional to the intensity of magnetic flux and the sign ofoutput signal is determined by the direction of magnetic flux. Herein,the pulse which appears on the leftmost in FIG. 18 is a pulse generatedby the magnetic flux formed by the reference magnetized region. FIG. 18shows that the intensity of pulse peak increases stepwise with time.Accordingly, in the case of FIG. 18, the control circuit judges that theshaft 302 rotates in the direction of increase of the intensity of Npole 336, i.e., counterclockwise as viewed from the sensor 340. Then,the control circuit counts the number of peaks detected per unit timeand calculates the rotary speed on the basis of the counted number ofpeaks and the interval at which the magnetized regions are disposed.

Further, the control circuit determines the absolute angle of the shafton the basis of the intensity of pulse peak. In the present embodiment,the output pulse of the sensor 340 has a flat gentle peak. Accordingly,the angle resolution is deteriorated as compared with the eleventhembodiment as in the case of the twelfth embodiment. The control circuithas a threshold value corresponding to the disposition angle of thevarious magnetized regions. Further, when the control circuit detectsthat the value detected exceeds the threshold value, it is judged thatthe encoder passes by the corresponding angle.

As mentioned above, in accordance with the present embodiment, theencoder 335 and the sensor 340 are disposed radially opposed to eachother. Further, the sensor-opposing surface of the encoder 335 is formedby a plurality of N poles 336 arranged such that the magnetic fluxdensity gradually increases. Accordingly, the single sensor 340 can beused to detect the speed, direction and angle of rotation of the shaft302 at the same time, making it possible to exert the same effect as inthe eleventh embodiment.

In the present embodiment, since the sensor-opposing surface of theencoder is formed by only N poles the magnetic flux density of whichgradually increase, the peak value thus detected is flat. Accordingly,as compared with the case where there is only one peak value, theoccurrence percentage of peak detection error is reduced, making itpossible to detect peak with a higher reliability.

While the present embodiment has been described with reference to thecase where the sensor-opposing surface of the encoder is formed by Npoles, the sensor-opposing surface of the encoder may be formed by Spoles. In this case, the detection of rotary speed, direction ofrotation and absolute angle is made in the same manner as in the presentembodiment except that the sign of output signal is inverted.

Further, in the present embodiment, since the outer ring 303 and innerring 304 as bearing, the encoder 335 and the sensor 340 are formedintegrally, assembly can be completed merely by disposing the bearingbetween the shaft and the housing if the encoder and the sensor havebeen previously mounted on the bearing. Accordingly, the efficiency inassembly can be enhanced, contributing to the reduction of assemblycost.

Moreover, the same rotation detecting device as in the presentembodiment can be applied to the bearing with sensor described in any ofthe first to tenth embodiments.

Fifteenth Embodiment

A fifteenth embodiment of implementation of the present invention willbe described hereinafter in connection with FIG. 23. Herein, the samemembers as mentioned in the eleventh to fourteenth embodiments will begiven the same reference numerals and signs and their description willbe omitted.

FIG. 23 illustrates a deep groove ball bearing as a rolling bearing withsensor having a rotation detecting device according to the thirteenth orfourteenth embodiment of implementation of the present inventionincorporated therein. In the present embodiment, the outer ring 303 andthe inner ring 304 of the deep groove ball bearing have a sensormounting portion 303 d and an encoder mounting portion 304 c whichextend axially, respectively.

On the axially outer side 304 d of the encoder mounting portion 304 c isdisposed an encoder 350. As the encoder 350 there may be used theencoder 330 or 335 described in the thirteenth or fourteenth embodiment.The axial side of the encoder 350 is opposed to the sensor mountingportion 303 d.

On the other hand, on the axially inner side 303 e of the sensormounting portion 303 d is provided standing an annular steel sheet 385.An annular seal 380 is supported by the steel sheet 385 to seal theclearance between the sensor mounting portion 303 d and the encodermounting portion 304 c.

Further, on the axially inner side 303 e of the sensor mounting member303 d is disposed a sensor mounting portion 375. The sensor mountingmember 375 is positioned between the seal ring 308 and the seal 380.

On the sensor mounting member 375 are disposed a temperature measuringdevice 370 and a sensor 360 formed by a hall element or the like. Thesensor 360 is disposed opposed to the encoder 350 and detects themagnetic flux formed by the encoder 350. The sensor 360 detects magneticflux and hence the rotary speed, rotation direction and absolute angleof rotary body in the same manner as in the thirteenth and fourteenthembodiments.

The temperature measuring device 370 measures the temperature of thesensor and encoder and the peripheral members and outputs thetemperature data thus measured to a control circuit which is not shown.The magnetized regions constituting the encoder 350 changes in magneticflux density with temperature change. The control circuit has a table bywhich the change of magnetic flux density with temperature change iscorrected. Further, the control circuit uses this table to correct theoutput value thus detected and detect the rotary speed, rotationdirection and absolute angle of the shaft. In the case where anoncontact type thermometer such as thermocouple is used, thetemperature of a nonrotary member such as sensor is detected, but in thecase where a noncontact type thermometer such as infrared radiationthermometer is used, the detection of the temperature of a rotary membersuch as encoder is made possible.

As mentioned above, in accordance with the present embodiment, outputvalue corrected in the light of temperature change can be used to detectthe rotary speed, rotation direction and absolute angle of the shaft.Accordingly, the encoder 350 can be used without taking into account theworking temperature conditions of the encoder 350, making it possible toapply the present rotary state detecting device to bearing and rollingdevice more widely.

The core gap between the encoder and the sensor changes with thermalexpansion and shrinkage. This core gap change may be corrected on thebasis of signal from the temperature measuring device.

Further, in the present embodiment, the encoder 350 and the sensor 360are sealed by the seal ring 308 and the seal 380. Therefore, theexternal effect can be minimized, making measurement possible at ahigher accuracy.

Moreover, the encoder 350 and the sensor 320 are disposed radiallyopposed to each other. Further, the encoder 310 is formed by a pluralityof N poles 312 and S poles 313 arranged such that the magnetic fluxdensity gradually increases. Accordingly, the single sensor 320 can beused to detect the speed, direction and angle of rotation of the shaft302 at the same time, making it possible to exert the same effect as inthe eleventh embodiment.

Further, the same rotation detecting device as in the present embodimentcan be applied to a bearing with sensor described in any of the first totenth embodiments.

Sixteenth Embodiment

A sixteenth embodiment of implementation of the present invention willbe described in detail in connection with FIGS. 24 to 28. FIG. 24illustrates a deep groove ball bearing as a rolling device having arotation detecting device according to the sixteenth embodiment ofimplementation of the present invention incorporated therein. The deepgroove ball bearing has an outer ring 403, an inner ring 404, aplurality of balls 407 as rolling element, a seal ring 408 and aretainer 409.

The outer ring 403 is fixed to the inner surface 401 a of a housing 401as a stationary member. The outer ring 403 is produced by subjecting ametallic material such as carbon steel to forging or the like. The outerring 403 has an outer ring race 405 provided on the inner surfacethereof for guiding the ball 407.

The inner ring 404 is produced by subjecting a metallic material such ascarbon steel to forging or the like similarly to the outer ring 403. Theinner ring 404 is fitted on the outer surface 402 a of a shaft 402 whichis a rotary member. The inner ring 404 has an inner ring race 406provided on the outer surface thereof corresponding to the outer ringrace 405 of the outer ring 403 for guiding the ball 407. The inner ring404 rotates integrally with the shaft 402 with the rotation of the shaft402.

The balls 407 are arranged in a line between the outer ring race 405 ofthe outer ring 403 and the inner ring race 406 of the inner ring 404.The balls 407 roll over the outer ring 405 and the inner ring 406 withthe rotation of the inner ring 404 accompanying the rotation of theshaft 402.

The seal ring 408 blocks and seals both the two openings of the spacereceiving the balls 407 between the outer ring 403 and the inner ring404. The seal ring 408 prevents the entrance of dust, water content,foreign matters, etc. into the space receiving the balls and the leakageof lubricant from the space receiving the balls. The seal ring 408 isfixed at a fixing portion 403 b formed on the inner surface of the outerring 403.

The retainer 409 retains the balls 407 rollably between the outer ringrace 405 and the inner ring race 406. As the retainer 409 there may beused a pressed cage, a machined cage or the like.

On the outer surface 402 a of the shaft 402 is provided standing anannular encoder retaining member 411. The encoder retaining member 411extends from the outer surface 402 a of the shaft 402 toward the housing401, i.e., outward radially from the shaft 402. On the axial side of theencoder retaining member 411 is provided an encoder 410 facing axially.

On the other hand, on the inner surface 401 a of the housing 401 isprovided standing a sensor retaining member 421. The sensor retainingmember 421 extends from the inner surface 401 a of the housing 401toward the shaft 402, i.e., inward radially from the housing 401. On theaxial side of the sensor retaining member 421 is provided a singlesensor 420. The sensor 420 is disposed axially opposed to the encoder410.

FIG. 25 is a plan view illustrating the encoder 410 and FIG. 26 is apartly enlarged perspective view of FIG. 25. The encoder 410 has anannular shape having a constant radial width. The encoder 410 has aplurality of stepped sensor-opposing surfaces 410 a and a flat encodermounting member grounding surface 410 b. The encoder 410 is fixed to anencoder mounting member 411 at the encoder mounting member groundingsurface 410 b. The normal direction of the encoder mounting membergrounding surface 410 b is the same as the axial direction.

As shown in FIG. 26, the plurality of sensor-opposing surfaces 410 a arecircumferentially separated by a step having an axial height h1. Thestep is formed every angle θ0 with the center O so that thesensor-opposing surface of the encoder is circumferentially dividedevery angle θ0. Accordingly, the height H from the encoder mountingmember grounding surface 410 b to the sensor-opposing surface 410 a ofthe encoder increases by h1 every angle θ0.

Accordingly, the axial height H of the encoder 410 increasesmonotonously by h1 every angle θ0 starting from the sensor-opposingsurface 410 a closest to the encoder mounting member grounding surface410 b as reference to the sensor-opposing surface 410 a farthest fromthe encoder mounting member grounding surface 410 b. In the presentembodiment, next to the sensor-opposing surface 410 a closest to theencoder mounting member grounding surface 410 b is disposed thesensor-opposing surface 410 a farthest from the encoder mounting membergrounding surface 410 b. Further, in the present embodiment, the encoder410 is disposed in such arrangement that the height H increases by h1counterclockwise as viewed from the sensor. Accordingly, the distancebetween the encoder 410 and the sensor 420 changes according to theshape of the sensor-opposing surface 410 a with the rotation of theshaft 402. The distance between the encoder 410 and the sensor 420 isstored in a control circuit which is not shown according to the angle.Moreover, the control circuit stores the position of the varioussensor-opposing surfaces 410 a and the absolute angle of the shaft 402in association with each other.

The sensor 420 is disposed axially opposed to the sensor-opposingsurface 410 a of the encoder 410. The sensor 420 is a displacementsensor which utilizes light or ultrasonic wave to measure the change ofthe distance between the sensor-opposing surface 410 a of the encoder410 and the sensor 420. The sensor 420 outputs light or ultrasonic wavetoward the sensor-opposing surface 410 a of the encoder 410. The lightor ultrasonic wave thus outputted is then reflected by thesensor-opposing surface 410 a. The sensor 420 receives the light orultrasonic wave thus reflected to measure the displacement of the shapeof the sensor-opposing surface. The sensor 420 outputs the distance datathus detected to a control circuit which is not shown via a cable 422.

FIG. 27 is a graph illustrating the output signal detected by the sensor420. In FIG. 27, the ordinate indicates the intensity of output signaland the abscissa indicates time. In FIG. 27, the broken line indicatesoutput signal. The magnitude of the output signal corresponds to thedistance from the sensor, and the closer to the sensor is thesensor-opposing surface, the greater is the intensity of output signal.Herein, the pulse appearing on the leftmost end in FIG. 27 indicates thepulse of value detected when the sensor-opposing surface 410 a closestto the encoder mounting member grounding surface 410 b is disposedopposed to the sensor 420. FIG. 27 shows that the intensity of pulsepeak increases stepwise monotonously with time.

As previously mentioned, in the present embodiment, the encoder 410 isprovided in such an arrangement that the height H gradually increases byh1 counterclockwise as viewed from the sensor 420. Accordingly, in thecase of FIG. 27, the control circuit judges that the encoder 410, i.e.,the shaft 402 rotates clockwise as viewed from the sensor.

As shown in FIG. 27, the output of the sensor 420 has a signal reflectedby the sensor-opposing surface 410 a closest to the sensor 420 as amaximum peak. The control circuit counts this maximum peak andcalculates the rotary speed of the shaft 402 on the basis of the numberof maximum peaks obtained per unit time.

Further, the control circuit determines the absolute angle of the shafton the basis of the pulse intensity. In the present embodiment, theoutput of the sensor 420 is stepwise according to the shape of theencoder 410. The control circuit stores the absolute angle of thevarious shapes and the detected value in association with each other.Then, the control circuit judges the angle at which the shaft isdisposed according to the detected value. In this manner, the detectionof the absolute angle of the shaft 402 can be made within the angleresolution range θ0.

As mentioned above, in accordance with the present embodiment, theencoder 410 and the sensor 420 are disposed axially opposed to eachother. Further, the encoder 410 has a sensor-opposing surface 410 aformed thereon such that the distance from the sensor 420 monotonouslyincreases or decreases. The sensor 420 is made of a displacement sensorutilizing light or ultrasonic wave. The sensor 420 outputs output signalaccording to the distance from the sensor-opposing surface 410 a to thecontrol circuit. The control circuit analyzes this output signal todetect the speed, direction and angle of rotation of the shaft 402.Accordingly, the single sensor 420 can be used to detect the speed,direction and angle of rotation of the shaft 402 at the same time,making it possible to exert the same effect as in the eleventhembodiment.

In the present embodiment, the sensor 420 is a displacement sensorutilizing light or ultrasonic wave. However, the sensor 420 is notspecifically limited so far as it is a sensor capable of measuring thechange of the distance between the sensor-opposing surface 410 a and thesensor 420. As the sensor 420 there may be proposed a magnetism sensor,a sensor utilizing interaction between magnetic field and eddy currentor the like by way of example. In the case where a magnetism sensor isused, the encoder is a magnetic material. In the case of a sensorutilizing eddy current, the encoder needs to be a ferromagnetic materialsuch as metallic material.

Seventeenth Embodiment

A seventeenth embodiment of implementation of the present invention willbe described hereinafter in connection with FIG. 28. Herein, the samemembers as mentioned in the sixteenth embodiment will be given the samereference numerals and signs and their description will be omitted.

In the present embodiment, in FIG. 24, on the axial side of an encoderretaining member 411 is disposed an encoder 415. On the other hand, onthe axial side of the sensor retaining member 421 is disposed a singlesensor 425. The sensor 425 is disposed axially opposed to the encoder415.

FIG. 28 is a partly enlarged perspective view of the encoder 415 used ina rotation detecting device according to the seventeenth embodiment ofimplementation of the present invention. In the present embodiment, theencoder 415 is disposed opposed to the sensor 425 similarly to theencoder 410.

The encoder 415 has an annular shape having a constant radial width. Theencoder 415 has a plurality of stepped sensor-opposing surfaces 415 aand a flat encoder mounting member grounding surface 415 b. The encoder415 is fixed to an encoder mounting member 411 at the encoder mountingmember grounding surface 415 b. The normal direction of the encodermounting member grounding surface 415 b is the same as the axialdirection.

As shown in FIG. 28, the plurality of sensor-opposing surfaces 415 a arecircumferentially separated by a step having an axial height h1. Thestep is formed every angle θ0 with the center O so that thesensor-opposing surface of the encoder is circumferentially dividedevery angle θ0. Accordingly, the height H from the encoder mountingmember grounding surface 415 b to the sensor-opposing surface 415 a ofthe encoder increases by h1 every angle θ0.

Accordingly, the axial height H of the encoder 415 increasesmonotonously by h1 every angle θ0 starting from the sensor-opposingsurface 415 a closest to the encoder mounting member grounding surface415 b as reference to the sensor-opposing surface 415 a farthest fromthe encoder mounting member grounding surface 415 b. In the presentembodiment, next to the sensor-opposing surface 415 a closest to theencoder mounting member grounding surface 415 b is disposed thesensor-opposing surface 415 a farthest from the encoder mounting membergrounding surface 415 b. Further, in the present embodiment, the encoder415 is disposed in such arrangement that the height H increases by h1counterclockwise as viewed from the sensor. Accordingly, the distancebetween the encoder 415 and the sensor 425 changes according to theshape of the sensor-opposing surface 415 a with the rotation of theshaft 402. The distance between the encoder 415 and the sensor 425 isstored in a control circuit which is not shown according to the angle.Moreover, the control circuit stores the position of the varioussensor-opposing surfaces 415 a and the absolute angle of the shaft 402in association with each other.

The sensor-opposing surfaces 415 a of the encoder 415 are each providedwith an N pole 437. The magnetized regions constituting the N pole 437each have a predetermined magnetic flux density. The N pole 437 formstherearound a magnetic field having an intensity corresponding to thepolarity and magnetic flux density thereof. Accordingly, a magneticfield corresponding to the magnetic flux density of N pole 437 is formedaround the encoder 415.

As the material of the encoder 415 there may be used an alnico magnet,ferrite magnet, samarium-cobalt magnet, neodymium-iron-boron magnet orbonded magnet obtained by mixing various magnet powders with a plasticor the like, molding the mixture and solidifying the molded material.Since the magnetic flux density of the various magnetized regions mustbe uniform, the bonded magnet, which can easily be designed to have anymagnetic flux density, is preferably used. Herein, a bonded magnet madeof a ferrite powder-containing plastic or rare earth material is used.The magnetic force of a magnet changes with temperature.

The sensor 425 is disposed axially opposed to the sensor-opposingsurface 415 a of the encoder 415. The sensor 425 is a magnetism sensorwhich measures the change of the distance between the sensor-opposingsurface 415 a of the encoder 415 and the sensor 425. The presentembodiment is described with reference to the use of a magnetism sensorcapable of detecting magnetic field such as hall element and coil,particularly hall element, by way of example. A hall element is anelement which generates electric current as output signal according tothe intensity and direction of magnetic flux crossing the hall element.

The sensor 425 senses the magnetic field formed by the various N poles437 of the encoder 415. The intensity of the magnetic field formed by Npole 437 increases or decreases as the distance between N pole 437 andthe sensor-opposing surface 415 a of the encoder 415 decreases orincreases, respectively. The sensor 425 senses the change of intensityof the magnetic field and outputs the detected value to a controlcircuit which is not shown via a cable 422.

The output signal detected by the sensor 425 is shown in FIG. 27. InFIG. 27, the solid line indicates output signal. The magnitude of theoutput signal is proportional to the intensity of magnetic flux detectedand the sign of output signal is determined by the direction of magneticflux. Herein, the pulse appearing on the leftmost end in FIG. 27indicates the pulse of value detected when the sensor-opposing surface415 a closest to the encoder mounting member grounding surface 415 b isdisposed opposed to the sensor 425. FIG. 27 shows that the intensity ofpulse peak increases substantially stepwise monotonously with time.

As previously mentioned, in the present embodiment, the encoder 415 isprovided in such an arrangement that the height H increases by h1counterclockwise as viewed from the sensor 425. Accordingly, in the caseof FIG. 27, the control circuit judges that the encoder 415, i.e., theshaft 402 rotates clockwise as viewed from the sensor.

As shown in FIG. 27, the output of the sensor 425 has a signal reflectedby the sensor-opposing surface 415 a closest to the sensor 425 as amaximum peak. The control circuit counts this maximum peak andcalculates the rotary speed of the shaft 402 on the basis of the numberof maximum peaks obtained per unit time.

Further, the control circuit determines the absolute angle of the shafton the basis of the pulse intensity. In the present embodiment, theoutput of the sensor 425 is stepwise according to the shape of theencoder 415. The control circuit stores the absolute angle of thevarious shapes and the detected value in association with each other.Then, the control circuit judges the angle at which the shaft isdisposed according to the detected value. In this manner, the detectionof the absolute angle of the shaft 402 can be made within the angleresolution range θ0.

As mentioned above, in accordance with the present embodiment, theencoder 415 and the sensor 425 are disposed axially opposed to eachother. Further, the encoder 415 has a sensor-opposing surface 415 aformed thereon such that the distance from the sensor 425 monotonouslyincreases or decreases. The sensor 425 is formed by a magnetism sensorand the sensor-opposing surface 415 a is provided with N pole 437. Thesensor 425 outputs output signal according to the distance from thesensor-opposing surface 415 a to the control circuit. The controlcircuit analyzes this output signal to detect the speed, direction andangle of rotation of the shaft 402. Accordingly, the single sensor 425can be used to detect the speed, direction and angle of rotation of theshaft 402 at the same time, making it possible to exert the same effectas in the eleventh embodiment.

In the present embodiment, since the sensor-opposing surface 415 a ofthe encoder is formed by only N poles, the peak value thus detected isflat. Accordingly, as compared with the case where there is only onepeak value, the occurrence percentage of peak detection error isreduced, making it possible to detect peak with a higher reliability.

While the present embodiment has been described with reference to thecase where the sensor-opposing surface of the encoder 415 is formed by Npoles, the sensor-opposing surface of the encoder 415 may be formed by Spoles. In this case, the detection of rotary speed, direction ofrotation and absolute angle is made in the same manner as in the presentembodiment except that the sign of output signal is inverted.

Eighteenth Embodiment

An eighteenth embodiment of implementation of the present invention willbe described hereinafter in connection with FIGS. 29 and 30. Herein, thesame members as mentioned in the sixteenth or seventeenth embodimentwill be given the same reference numerals and signs and theirdescription will be omitted.

In the present embodiment, in FIG. 24, on the axial side of the encoderretaining member 411 is disposed an encoder 416. On the other hand, onthe axial side of the sensor retaining member 421 is disposed a singlesensor 425. The sensor 425 is disposed axially opposed to the encoder416.

FIG. 29 is a partly enlarged perspective view of the encoder 416 used ina rotation detecting device according to the eighteenth embodiment ofimplementation of the present invention. In the present embodiment, theencoder 416 is disposed opposed to the sensor 425 similarly to theencoders 410 and 415.

The encoder 416 has an annular shape having a constant radial width. Theencoder 416 has a plurality of stepped sensor-opposing surfaces 416 aand a flat encoder mounting member grounding surface 416 b. The encoder416 is fixed to the encoder mounting member 411 at the encoder mountingmember grounding surface 416 b. The normal direction of the encodermounting member grounding surface 416 b is the same as the axialdirection.

As shown in FIG. 29, the plurality of sensor-opposing surfaces 416 a arecircumferentially separated by a step having an axial height l1. Thestep is formed every angle θ0 with the center O so that thesensor-opposing surface of the encoder is circumferentially dividedevery angle θ0. Accordingly, the height L from the encoder mountingmember grounding surface 416 b to the sensor-opposing surface 416 a ofthe encoder increases by l1 every angle θ0.

Accordingly, the axial height L of the encoder 416 increasesmonotonously by l1 every angle θ0 starting from the sensor-opposingsurface 416 a closest to the encoder mounting member grounding surface416 b as reference to the sensor-opposing surface 416 a farthest fromthe encoder mounting member grounding surface 416 b. In the presentembodiment, next to the sensor-opposing surface 416 a closest to theencoder mounting member grounding surface 416 b is disposed thesensor-opposing surface 416 a farthest from the encoder mounting membergrounding surface 416 b. Further, in the present embodiment, the encoder416 is disposed in such arrangement that the height L increases by l1counterclockwise as viewed from the sensor. Accordingly, the distancebetween the encoder 416 and the sensor 425 changes according to theshape of the sensor-opposing surface 416 a with the rotation of theshaft 402. The distance between the encoder 416 and the sensor 425 isstored in a control circuit which is not shown according to the angle.Moreover, the control circuit stores the position of the varioussensor-opposing surfaces 416 a and the absolute angle of the shaft 402in association with each other.

The sensor-opposing surfaces 416 a of the encoder 416 are each providedwith a plurality of N poles 437 and S poles 438. The magnetized regionsconstituting the N pole 437 and S pole 438 each have a predeterminedmagnetic flux density. The N pole 437 and S pole 438 each formtherearound a magnetic field having an intensity corresponding to thepolarity and magnetic flux density thereof. Accordingly, a magneticfield corresponding to the magnetic flux density of N pole 437 and Spole 438 is formed around the encoder 416.

As the material of the encoder 416 there may be used an alnico magnet,ferrite magnet, samarium-cobalt magnet, neodymium-iron-boron magnet orbonded magnet obtained by mixing various magnet powders with a plasticor the like, molding the mixture and solidifying the molded material.Since the magnetic flux density of the various magnetized regions mustbe uniform, the bonded magnet, which can easily be designed to have anymagnetic flux density, is preferably used. Herein, a bonded magnet madeof a ferrite powder-containing plastic or rare earth material is used.The magnetic force of a magnet changes with temperature.

The sensor 425 is a magnetism sensor capable of detecting magnetic fieldsuch as hall element and coil as explained in the seventeenthembodiment.

The sensor 425 senses the magnetic field formed by the various N poles437 and S poles 438 of the encoder 415. The absolute value of theintensity of the magnetic field formed by N pole 437 and S pole 438increases or decreases as the distance between N pole 437 or S pole 438and the sensor-opposing surface 416 a of the encoder 416 decreases orincreases, respectively. The sensor 425 senses the change of intensityof the magnetic field and outputs the detected value to a controlcircuit which is not shown via a cable 422.

FIG. 30 illustrates the output signal detected by the sensor 425. Themagnitude of the output signal is proportional to the intensity ofmagnetic flux detected and the sign of output signal is determined bythe direction of magnetic flux. Herein, the pulse appearing on theleftmost end in FIG. 30 indicates the pulse of value detected when thesensor-opposing surface 416 a closest to the encoder mounting membergrounding surface 416 b is disposed opposed to the sensor 425. FIG. 30shows that the absolute value of the intensity of pulse peak increasessubstantially stepwise monotonously with time.

As previously mentioned, in the present embodiment, the encoder 416 isprovided in such an arrangement that the height L increases by l1counterclockwise as viewed from the sensor 425. Accordingly, in the caseof FIG. 27, the control circuit judges that the encoder 416, i.e., theshaft 402 rotates clockwise as viewed from the sensor.

As shown in FIG. 30, the output of the sensor 425 has a signal reflectedby the sensor-opposing surface 416 a closest to the sensor 425 as amaximum peak. The control circuit counts this maximum peak andcalculates the rotary speed of the shaft 402 on the basis of the numberof maximum peaks obtained per unit time.

Further, the control circuit determines the absolute angle of the shaft402 on the basis of the peak intensity. When the output of the sensor425 shows the detection of peak (point A in FIG. 30), the controlcircuit judges that the magnetized region corresponding to the outputthus detected is disposed opposed to the sensor 425. Then, the controlcircuit judges that the shaft 402 is disposed at the absolute anglecorresponding to the magnetized region thus detected.

Further, when the output of the sensor 425 is the value at point B inbetween the peaks, the absolute angle of point B is calculated from theratio of intensity at point A, which is the immediately previous peak,to the difference between the intensity at point A and at point B. Insome detail, the angle at point B is calculated by Equation 2 asdescribed above.

The control circuit stores the position of the various sensor-opposingsurfaces 416 a and the absolute angle of the shaft 402 in associationwith each other. Accordingly, the control circuit calculates theabsolute angle of the encoder referring to the results of calculation byEquation 2 as described above.

As mentioned above, in accordance with the present embodiment, theencoder 416 and the sensor 425 are disposed axially opposed to eachother. Further, the encoder 416 has a sensor-opposing surface 416 aformed thereon such that the distance from the sensor 425 monotonouslyincreases or decreases. The sensor 425 is formed by a magnetism sensorand on the sensor-opposing surface 416 a are disposed alternately Npoles 437 and S poles 438. The sensor 425 outputs output signalaccording to the distance from the sensor-opposing surface 416 a to thecontrol circuit. The control circuit analyzes this output signal todetect the speed, direction and angle of rotation of the shaft 402.Accordingly, the single sensor 425 can be used to detect the speed,direction and angle of rotation of the shaft 402 at the same time,making it possible to exert the same effect as in the eleventhembodiment.

In the present embodiment, an encoder having a sensor-opposing surfaceformed by N poles and S poles was used. Accordingly, the peak thusdetected is sharp, making it possible to detect the absolute angle at ahigher angle resolution than in the sixteenth embodiment or seventeenthembodiment.

Nineteenth Embodiment

A nineteenth embodiment of implementation of the present invention willbe described in detail hereinafter in connection with FIGS. 31 to 33.Herein, the same members as mentioned in the sixteenth to nineteenthembodiments will be given the same reference numerals and signs andtheir description will be omitted.

FIG. 31 illustrates a deep groove ball bearing as a bearing with sensorhaving a rotation detecting device according to the nineteenthembodiment of implementation of the present invention incorporatedtherein. The deep groove ball bearing has an outer ring 403, an innerring 404, a plurality of balls 407 as rolling element, a seal ring 408and a retainer 409.

In the present embodiment, the seal ring 408 blocks and seals one ofboth the two openings of the space receiving the balls 407 between theouter ring 403 and the inner ring 404. The other of both the twoopenings of the balls 407 is blocked and sealed by an encoder retainingmember 431 and a sensor retaining member 441.

The sensor retaining member 441 is an annular member having a C-shapedsection with two parallel ends. The sensor retaining member 441 is fixedto the axial end 403 c of the outer ring 403 and protrudes axially fromthe outer ring 403. On the radially inner top side of the sensorretaining member 441 is disposed a sensor 440 facing radially.

The encoder retaining member 431 is an annular member having an L-shapedsection. The encoder retaining member 431 is fixed to the axial end 4 bof the inner ring 404 and protrudes axially from the inner ring 402. Theforward end of the sensor retaining member 441 is disposed between boththe two ends of the sensor retaining member 441. The encoder retainingmember 431 and the sensor retaining member 441 play the same role as theseal ring 408 in cooperation with each other. On the radial side of theencoder retaining member 431 is disposed an encoder 430. The encoder 430is disposed radially opposed to the sensor 440.

FIG. 32 is a plan view illustrating the encoder 430 and FIG. 33 is apartly enlarged view of FIG. 32. The encoder 430 is made of a materialwhich can be easily magnetized such as ferromagnetic material. Theencoder 430 has an annular shape having a constant axial width. Theencoder 430 has an encoder mounting member grounding surface 430 b apartfrom the center of the ring by a radius of R2 and a plurality ofsensor-opposing surfaces 430 a disposed at positions apart from thecenter O of the ring by radii R1 which vary every predetermined angleθ0. The encoder 430 is fixed to the encoder mounting member 431 at theencoder mounting member grounding surface 430 b. The normal direction ofthe encoder mounting member grounding surface 430 b crosses the axialdirection.

As shown in FIG. 33, the plurality of sensor-opposing surfaces 430 a arecircumferentially separated by a step having a radial height r1. Thestep is formed every angle θ0 with the center O so that thesensor-opposing surface of the encoder 430 is circumferentially dividedevery angle θ0. Accordingly, the radius R1 from the center O of theencoder 430 to the sensor-opposing surface 430 a of the encoder 430increases by r1 every angle θ0.

Accordingly, the radius R1 of the encoder 430 gradually increases by r1every angle θ0 starting from the sensor-opposing surface 430 a havingthe smallest radius R1 as reference to the sensor-opposing surface 430 ahaving the greatest radius R1. In the present embodiment, next to thesensor-opposing surface 430 a having the smallest radius R1 is disposedthe sensor-opposing surface 430 a having the greatest radius R1.Further, in the present embodiment, the encoder 430 is disposed in sucharrangement that the radius R1 gradually increases clockwise as viewedaxially (arrow A in FIG. 31). Accordingly, the distance between theencoder 430 and the sensor 440 changes according to the shape of thesensor-opposing surface 430 a with the rotation of the shaft 402. Thedistance between the encoder 430 and the sensor 440 is stored in acontrol circuit which is not shown according to the angle. Moreover, thecontrol circuit stores the position of the various sensor-opposingsurfaces 430 a and the absolute angle of the shaft 402 in associationwith each other.

Further, the encoder 430 may be disposed in such an arrangement that theradius R1 gradually increases counterclockwise as viewed axially (arrowA in FIG. 31).

The sensor 440 is disposed radially opposed to the sensor-opposingsurface 430 a of the encoder 430. The sensor 440 is a displacementsensor which measures the change of the distance between thesensor-opposing surface 430 a of the encoder 430 and the sensor 440. Thesensor 440 outputs light or ultrasonic wave toward the sensor-opposingsurface 430 a of the encoder 430 similarly to the sensor 420 of thesixteenth embodiment. The light or ultrasonic wave thus outputted isthen reflected by the sensor-opposing surface 430 a. The sensor 440receives the light or ultrasonic wave thus reflected to measure thedisplacement of the shape of the sensor-opposing surface. The sensor 440outputs the distance data thus detected to a control circuit which isnot shown via a cable 422.

The output signal detected by the sensor 440 is the same as indicated bythe broken line in FIG. 27. Herein, the pulse appearing on the leftmostend in FIG. 27 indicates the pulse of value detected when thesensor-opposing surface 430 a having the smallest radius R1 is disposedopposed to the sensor 440. FIG. 27 shows that the absolute value of theintensity of pulse peak increases stepwise monotonously with time.

As previously mentioned, in the present embodiment, the encoder 430 isprovided in such an arrangement that the radius R1 gradually increasesclockwise as viewed axially (arrow A in FIG. 31). Accordingly, in thecase of FIG. 27, the control circuit judges that the encoder 430, i.e.,the shaft 402 rotates counterclockwise as viewed axially (arrow A inFIG. 31).

Further, the control circuit counts the number of maximum peaks ofdetected signal and calculates the rotary speed of the shaft 402 on thebasis of the number of maximum peaks obtained per unit time as in thesixteenth embodiment.

Further, the control circuit determines the absolute angle of the shafton the basis of the pulse intensity. In the present embodiment, theoutput of the sensor 440 is stepwise according to the shape of theencoder 430. The control circuit stores the absolute angle of thevarious shapes and the detected value in association with each other.Then, the control circuit judges the angle at which the shaft isdisposed according to the detected value. In this manner, the detectionof the absolute angle of the shaft 402 can be made within the angleresolution range θ0.

As mentioned above, in accordance with the present embodiment, theencoder 430 and the sensor 440 are disposed radially opposed to eachother. Further, the encoder 430 has a sensor-opposing surface 430 aformed thereon such that the distance from the sensor 440 monotonouslyincreases or decreases. The sensor 440 is made of a displacement sensorutilizing light or ultrasonic wave. The sensor 440 outputs output signalaccording to the distance from the sensor-opposing surface 430 a to thecontrol circuit. The control circuit analyzes this output signal todetect the speed, direction and angle of rotation of the shaft 402.Accordingly, the single sensor 440 can be used to detect the speed,direction and angle of rotation of the shaft 402 at the same time,making it possible to exert the same effect as in the eleventhembodiment.

In the present embodiment, the sensor 440 is a displacement sensorutilizing light or ultrasonic wave. However, the sensor 440 is notspecifically limited so far as it is a sensor capable of measuring thechange of the distance between the sensor-opposing surface 430 a and thesensor 440. As the sensor 440 there may be proposed a magnetism sensor,a sensor utilizing interaction between magnetic field and eddy currentor the like by way of example. In the case where a magnetism sensor isused, the encoder is a magnetic material. In the case of a sensorutilizing eddy current, the encoder needs to be a ferromagnetic materialsuch as metallic material.

Further, the rotation detecting device as in the present embodiment canbe applied to a bearing with sensor described in any of the first totenth embodiments.

Twentieth Embodiment

A twentieth embodiment of implementation of the present invention willbe described hereinafter in connection with FIG. 34. Herein, the samemembers as mentioned in the sixteenth to nineteenth embodiments will begiven the same reference numerals and signs and their description willbe omitted.

In the present embodiment, in FIG. 31, on the radial side of an encoderretaining member 411 is disposed an encoder 435 radially. On the otherhand, on the radial side of a sensor retaining member 441 is disposed asingle sensor 445. The sensor 445 is disposed radially opposed to theencoder 435.

FIG. 34 is a partly enlarged perspective view of the encoder 435 used ina rotation detecting device according to the twentieth embodiment ofimplementation of the present invention. In the present embodiment, theencoder 435 is disposed opposed to the sensor 445 similarly to theencoder 430.

The encoder 435 has an annular shape having a constant axial width. Theencoder 435 has an encoder mounting member grounding surface 435 b apartfrom the center O of the ring by a radius of R2 and a plurality ofsensor-opposing surfaces 435 a disposed at positions apart from thecenter O of the ring by radii R1 which vary every predetermined angleθ0. The encoder 435 is fixed to the encoder mounting member 431 at theencoder mounting member grounding surface 435 b. The normal direction ofthe encoder mounting member grounding surface 435 b crosses the axialdirection.

As shown in FIG. 34, the plurality of sensor-opposing surfaces 435 a arecircumferentially separated by a step having a radial height r1 of theencoder 435. The step is formed every angle θ0 with the center O so thatthe sensor-opposing surface of the encoder 435 is circumferentiallydivided every angle θ0. Accordingly, the radius R1 from the center O ofthe encoder 435 to the sensor-opposing surface 435 a increases by r1every angle θ0.

Accordingly, the radius R1 of the encoder 435 increases monotonously byr1 every angle θ0 starting from the sensor-opposing surface 435 a havingthe smallest radius R1 as reference to the sensor-opposing surface 435 ahaving the greatest radius R1. In the present embodiment, next to thesensor-opposing surface 435 a having the smallest radius R1 is disposedthe sensor-opposing surface 435 a having the greatest radius R1.Further, in the present embodiment, the encoder 435 is disposed in sucharrangement that the radius R1 increases by r1 clockwise as viewedaxially (arrow A in FIG. 31). Accordingly, the distance between theencoder 435 and the sensor 445 changes according to the shape of thesensor-opposing surface 435 a with the rotation of the shaft 402. Thedistance between the encoder 435 and the sensor 445 is stored in acontrol circuit which is not shown according to the angle. Moreover, thecontrol circuit stores the position of the various sensor-opposingsurfaces 435 a and the absolute angle of the shaft 402 in associationwith each other.

The sensor-opposing surfaces 435 a of the encoder 435 are each providedwith an N pole 437. The magnetized regions constituting the N pole 437each have a predetermined magnetic flux density. The N pole 437 formstherearound a magnetic field having an intensity corresponding to thepolarity and magnetic flux density thereof. Accordingly, a magneticfield corresponding to the magnetic flux density of N pole 437 is formedaround the encoder 435.

The sensor 445 is disposed radially opposed to the sensor-opposingsurface 435 a of the encoder 435. The sensor 35 is a displacement sensorwhich measures the change of the distance between the sensor-opposingsurface 435 a of the encoder 435 and the sensor 445. The presentembodiment is described with reference to the use of a magnetism sensorcapable of detecting magnetic field such as hall element and coil,particularly hall element, by way of example. A hall element is anelement which generates electric current as output signal according tothe intensity and direction of magnetic flux crossing the hall element.

The sensor 445 senses the magnetic field formed by the various N poles437 of the encoder 435. The intensity of the magnetic field formed by Npole 437 increases or decreases as the distance between N pole 437 andthe sensor-opposing surface 435 a of the encoder 435 decreases orincreases, respectively. The sensor 445 senses the change of intensityof the magnetic field and outputs the detected value to a controlcircuit which is not shown via a cable 422.

The pattern of value detected is as indicated by the solid line in FIG.27 as in the seventeenth embodiment. The magnitude of the output signalis proportional to the intensity of magnetic flux and the sign of outputsignal is determined by the direction of magnetic flux. Herein, thepulse appearing on the leftmost end in FIG. 27 indicates the pulse ofvalue detected when the sensor-opposing surface 435 a having thesmallest radius R1 is disposed opposed to the sensor 445. FIG. 27 showsthat the absolute value of the intensity of pulse peak increasesstepwise gradually with time.

As previously mentioned, in the present embodiment, the encoder 435 isprovided in such an arrangement that the radius R1 gradually increasesclockwise as viewed axially (arrow A in FIG. 31). Accordingly, in thecase of FIG. 27, the control circuit judges that the encoder 435, i.e.,the shaft 402 rotates counterclockwise as viewed axially (arrow A inFIG. 31).

As shown in FIG. 27, the output of the sensor 445 has a signal reflectedby the sensor-opposing surface 435 a disposed closest to the sensor 445as a maximum peak. The control circuit counts this peak and calculatesthe rotary speed of the shaft 402 on the basis of the number of maximumpeaks obtained per unit time.

Further, the control circuit determines the absolute angle of the shaft402 on the basis of the pulse intensity. In the case of the presentembodiment, the output of the pulse of the sensor 445 is substantiallystepwise according to the shape of the encoder 435. The control circuitstores the absolute angle of the various shapes and the detected valuein association with each other. Then, the control circuit judges theangle at which the shaft is disposed according to the detected value. Inthis manner, the detection of the absolute angle of the shaft 402 can bemade within the angle resolution range θ0.

As mentioned above, in accordance with the present embodiment, theencoder 435 and the sensor 445 are disposed radially opposed to eachother. Further, the encoder 435 has a sensor-opposing surface 435 aformed thereon such that the distance from the sensor 445 monotonouslyincreases or decreases. The sensor 445 outputs output signal accordingto the distance from the sensor-opposing surface 435 a to the controlcircuit. The control circuit analyzes this output signal to detect thespeed, direction and angle of rotation of the shaft 402. Accordingly,the single sensor 445 can be used to detect the speed, direction andangle of rotation of the shaft 402 at the same time, making it possibleto exert the same effect as in the eleventh embodiment.

In the present embodiment, since on the sensor-opposing surface 435 a isdisposed by only N poles, the peak value thus detected is flat.

In the present embodiment, since the sensor-opposing surface 435 a isformed by only N poles, the peak value thus detected is flat.Accordingly, as compared with the case where there is only one peakvalue, the percent occurrence of peak detection error is reduced, makingit possible to detect peak with a higher reliability.

While the present embodiment has been described with reference to thecase where the sensor-opposing surface of the encoder 435 is formed by Npoles, the sensor-opposing surface of the encoder 435 may be formed by Spoles. In this case, the detection of rotary speed, direction ofrotation and absolute angle is made in the same manner as in the presentembodiment except that the sign of output signal is inverted.

Further, the same rotation detecting device as in the present embodimentcan be applied to a bearing with sensor described in any of the first totenth embodiments.

Twenty First Embodiment

A twenty first embodiment of implementation of the present inventionwill be described hereinafter in connection with FIG. 35. Herein, thesame members as mentioned in the sixteenth to twentieth embodiments willbe given the same reference numerals and signs and their descriptionwill be omitted.

In the present embodiment, in FIG. 31, on the radial side of the encoderretaining member 431 is disposed an encoder 436. On the other hand, onthe axial side of the sensor retaining member 441 is disposed a singlesensor 445. The sensor 445 is disposed radially opposed to the encoder436.

FIG. 35 is a partly enlarged perspective view of the encoder 436 used ina rotation detecting device according to the twenty first embodiment ofimplementation of the present invention. In the present embodiment, theencoder 436 is disposed opposed to the sensor 445 similarly to theencoder 430 or 435.

The encoder 436 has an annular shape having a constant axial width. Theencoder 436 has an encoder mounting member grounding surface 436 b apartfrom the center O of the ring by a radius of R2 and a plurality ofsensor-opposing surfaces 436 a disposed at positions apart from thecenter O of the ring by radii R1 which vary every predetermined angleθ0. The encoder 436 is fixed to the encoder mounting member 431 at theencoder mounting member grounding surface 436 b. The normal direction ofthe encoder mounting member grounding surface 436 b crosses the axialdirection.

As shown in FIG. 35, the plurality of sensor-opposing surfaces 436 a arecircumferentially separated by a step having an axial height r1. Thestep is formed every angle θ0 with the center O so that thesensor-opposing surface of the encoder 436 is circumferentially dividedevery angle θ0. Accordingly, the radius R1 from the center O of theencoder 436 to the sensor-opposing surface 436 a of the encoder 436increases by r1 every angle θ0.

Accordingly, the radius R1 of the encoder 436 gradually increases by r1every angle θ0 starting from the sensor-opposing surface 436 a havingthe smallest radius R1 as reference to the sensor-opposing surface 436 ahaving the greatest radius R1. In the present embodiment, next to thesensor-opposing surface 436 a having the smallest radius R1 is disposedthe sensor-opposing surface 436 a having the greatest radius R1.Further, in the present embodiment, the encoder 436 is disposed in sucharrangement that the radius R1 gradually increases clockwise as viewedaxially (arrow A in FIG. 31). Accordingly, the distance between theencoder 436 and the sensor 445 changes according to the shape of thesensor-opposing surface 436 a with the rotation of the shaft 402.

The distance between the encoder 436 and the sensor 445 is stored in acontrol circuit which is not shown according to the angle. Moreover, thecontrol circuit stores the position of the various sensor-opposingsurfaces 436 a and the absolute angle of the shaft 402 in associationwith each other.

On the sensor-opposing surface 436 a of the encoder 436 are disposed aplurality of N poles 437 and S poles 438 arranged alternately. Themagnetized regions constituting the N pole 437 and S pole 438 each havea predetermined magnetic flux density. The N pole 437 and S pole 438each form therearound a magnetic field having an intensity correspondingto the polarity and magnetic flux density thereof. Accordingly, amagnetic field corresponding to the magnetic flux density of N pole 437and S pole 438 is formed around the encoder 436.

The sensor 445 is a magnetism sensor capable of detecting magnetic fieldsuch as hall element and coil as explained in the twentieth embodiment.

The sensor 445 senses the magnetic field formed by the various N poles437 and S poles 438 of the encoder 436. The absolute value of theintensity of the magnetic field formed by N pole 437 and S pole 438increases or decreases as the distance between N pole 437 or S pole 438and the sensor-opposing surface 436 a of the encoder 436 decreases orincreases, respectively. The sensor 445 senses the change of intensityof the magnetic field and outputs the detected value to a controlcircuit which is not shown via a cable 422.

The output signal detected by the sensor 445 is the same as shown inFIG. 30. Herein, the pulse appearing on the leftmost end in FIG. 30indicates the pulse of value detected when the sensor-opposing surface436 a having the smallest radius R1 is disposed opposed to the sensor445. FIG. 30 shows that the sign of the pulse peak is inverted dependingon the difference of polarity and the absolute value of the intensity ofpulse peak increases with time. Accordingly, in the case of FIG. 30, thecontrol circuit judges that the shaft 402 rotates in the direction ofincrease of the intensity of N pole 437 or S pole 438, i.e.,counterclockwise as viewed axially (arrow A in FIG. 31). Then, thecontrol circuit counts the number of peaks detected per unit time andcalculates the rotary speed of the shaft 402.

Further, the control circuit determines the absolute angle of the shaft402 on the basis of the intensity of pulse peak. The control circuitcalculates the absolute angle on the basis of Equation 2 described aboveas in the eighteenth embodiment.

The control circuit stores the position of the various sensor-opposingsurfaces 436 a and the absolute angle of the shaft 402 in associationwith each other. Accordingly, the control circuit calculates theabsolute angle of the encoder 436 referring to the results ofcalculation by Equation 2 as described above.

As mentioned above, in accordance with the present embodiment, theencoder 436 and the sensor 445 are disposed radially opposed to eachother. Further, the encoder 436 has a sensor-opposing surface 436 aformed thereon such that the distance from the sensor 445 monotonouslyincreases or decreases. The sensor 445 outputs output signal accordingto the distance from the sensor-opposing surface 436 a to the controlcircuit. The control circuit analyzes this output signal to detect thespeed, direction and angle of rotation of the shaft 402. Accordingly,the single sensor 445 can be used to detect the speed, direction andangle of rotation of the shaft 402 at the same time, making it possibleto exert the same effect as in the eleventh embodiment.

In the present embodiment, the encoder 436 having a sensor-opposingsurface formed by N poles and S poles was used. Accordingly, the peakdetected is sharp, making it possible to detect absolute angle at a highangle resolution as in the eighteenth embodiment.

Further, the same rotation detecting device as in the present embodimentcan be applied to a bearing with sensor described in any of the first totenth embodiments.

Twenty Second Embodiment

A twenty second embodiment of implementation of the present inventionwill be described hereinafter in connection with FIGS. 36 to 38. Herein,the same members as mentioned in the sixteenth to twenty firstembodiments will be given the same reference numerals and signs andtheir description will be omitted.

FIG. 36 is a plan view illustrating an encoder 450 in the twenty secondembodiment of implementation of the present invention. The encoder 450is used instead of the encoder 430 of FIG. 31. Configurations other thanthe encoder 450 are as shown in FIG. 31.

FIG. 37 is a partly enlarged perspective view of the encoder 450. Theencoder 450 has an annular shape having a constant axial width. Theencoder 450 has an encoder mounting member grounding surface 450 b apartfrom the center O of the ring by a radius of R2 and sensor-opposingsurfaces 450 a disposed at positions apart from the center O of the ringby radii R1 which gradually increase or decrease. The encoder 450 isfixed to the encoder mounting member 431 at the encoder mounting membergrounding surface 450 b. The normal direction of the encoder mountingmember grounding surface 450 b crosses the axial direction. Thesensor-opposing surface 450 a of the encoder 450 is disposed radiallyopposed to the sensor 440, which is a displacement sensor.

The radius R1 of the encoder 450 increases at a predetermined ratio asthe angle increases along the circumferential direction from thereference position. The position at which the radius R1 is at maximumand the position at which the radius R1 is at minimum are separated by astep. In the present embodiment, the encoder is disposed in sucharrangement that the radius R1 gradually increases clockwise as viewedaxially (arrow A in FIG. 31). Accordingly, the distance between theencoder 450 and the sensor 440 changes according to the shape of thesensor-opposing surface 450 a with the rotation of the shaft 402. Thedistance between the encoder 450 and the sensor 440 is stored in acontrol circuit which is not shown according to the angle. Moreover, thecontrol circuit stores the position of the various sensor-opposingsurfaces 450 a and the absolute angle of the shaft 402 in associationwith each other.

FIG. 38 is a diagram illustrating the output signal detected by thesensor 440. FIG. 38 shows that the detected signal gradually increaseslinearly with time.

As previously mentioned, in the present embodiment, the encoder 450 isprovided in such an arrangement that the radius R1 gradually increasesclockwise as viewed axially (arrow A in FIG. 31). Accordingly, in thecase of FIG. 38, the control circuit judges that the encoder 450, i.e.,the shaft 402 rotates counterclockwise as viewed axially (arrow A inFIG. 31).

Further, the control circuit samples the time at which the peak reachesmaximum and calculates the rotary speed from the time required from apeak to next peak.

Further, the control circuit determines the absolute angle of the shafton the basis of the peak intensity. In the case of the presentembodiment, the control circuit further has a predetermined angle and atable of detected values corresponding to the angle. The control circuitcompares this table with the intensity of output value detected tocalculate the rotary speed of the shaft 402.

As mentioned above, in accordance with the present embodiment, theencoder 450 and the sensor 440 are disposed radially opposed to eachother. Further, the encoder 450 has a sensor-opposing surface 450 aformed thereon such that the distance from the sensor 440 graduallyincreases or decreases. The sensor 440 outputs output signal accordingto the distance from the sensor-opposing surface 450 a to the controlcircuit. The control circuit analyzes this output signal to detect thespeed, direction and angle of rotation of the shaft 402. Accordingly,the single sensor 440 can be used to detect the speed, direction andangle of rotation of the shaft 402 at the same time, making it possibleto exert the same effect as in the eleventh embodiment.

Further, the same rotation detecting device as in the present embodimentcan be applied to a bearing with sensor described in any of the first totenth embodiments.

Twenty Third Embodiment

A twenty third embodiment of implementation of the present inventionwill be described hereinafter in connection with FIGS. 39 to 40. Herein,the same members as mentioned in the sixteenth to twenty secondembodiments will be given the same reference numerals and signs andtheir description will be omitted.

FIG. 39 is a partly enlarged perspective view illustrating the encoder455 in the twenty third embodiment of implementation of the presentinvention. The encoder 455 is used instead of the encoder 430 of FIG.31. Configurations other than the encoder 455 are as shown in FIG. 31.

The encoder 455 has an annular shape having a constant axial width. Theencoder 455 has an encoder mounting member grounding surface 455 b apartfrom the center O of the ring by a radius of R2 and sensor-opposingsurfaces 455 a disposed at positions apart from the center O of the ringby radii R1 which gradually increase. The encoder 455 is fixed to theencoder mounting member 431 at the encoder mounting member groundingsurface 455 b. The normal direction of the encoder mounting membergrounding surface 455 b crosses the axial direction. The sensor-opposingsurface 455 a of the encoder 455 is disposed radially opposed to thesensor 445, which is a magnetism sensor.

The radius R1 of the encoder 455 increases at a predetermined ratio asthe angle increases along the circumferential direction from thereference position. The position at which the radius R1 is at maximumand the position at which the radius R1 is at minimum are separated by astep. In the present embodiment, the encoder is disposed in sucharrangement that the radius R1 gradually increases clockwise as viewedaxially (arrow A in FIG. 31). Accordingly, the distance between theencoder 455 and the sensor 445 changes according to the shape of thesensor-opposing surface 455 a with the rotation of the shaft 402. Thedistance between the encoder 455 and the sensor 445 is stored in acontrol circuit which is not shown according to the angle. Moreover, thecontrol circuit stores the position of the various sensor-opposingsurfaces 455 a and the absolute angle of the shaft 402 in associationwith each other.

On the sensor-opposing surface 455 a of the encoder 455 are disposed aplurality of N poles 437 and S poles 438 arranged alternately at apredetermined interval. The magnetized regions constituting the N pole437 and S pole 438 each have a predetermined magnetic flux density. TheN pole 437 and S pole 438 each form therearound a magnetic field havingan intensity corresponding to the polarity and magnetic flux densitythereof. Accordingly, a magnetic field corresponding to the magneticflux density of N pole 437 and S pole 438 is formed around the encoder455.

FIG. 40 is a diagram illustrating the output signal detected by thesensor 445. Herein, FIG. 40 shows that the absolute value of intensityof pulse peak gradually increases with time.

As previously mentioned, in the present embodiment, the encoder 455 isprovided in such an arrangement that the radius R1 gradually increasesclockwise as viewed axially (arrow A in FIG. 31). Accordingly, in thecase of FIG. 40, the control circuit judges that the encoder 455, i.e.,the shaft 402 rotates counterclockwise as viewed axially (arrow A inFIG. 31).

Further, the control circuit samples the time at which the peak reachesmaximum and calculates the rotary speed from the time required from apeak to next peak.

Further, the control circuit determines the absolute angle of the shafton the basis of the intensity of detected signal. In the case of thepresent embodiment, the control circuit further has a predeterminedangle and a table of detected values corresponding to the angle. Thecontrol circuit compares this table with the intensity of output valuedetected to calculate the rotary speed of the shaft 402.

As mentioned above, in accordance with the present embodiment, theencoder 455 and the sensor 445 are disposed radially opposed to eachother. Further, the encoder 455 has a sensor-opposing surface 455 aformed thereon such that the distance from the sensor 445 graduallyincreases or decreases. The sensor 445 outputs output signal accordingto the distance from the sensor-opposing surface 455 a to the controlcircuit. The control circuit analyzes this output signal to detect thespeed, direction and angle of rotation of the shaft 402. Accordingly,the single sensor 445 can be used to detect the speed, direction andangle of rotation of the shaft 402 at the same time, making it possibleto exert the same effect as in the eleventh embodiment.

Further, the same rotation detecting device as in the present embodimentcan be applied to a bearing with sensor described in any of the first totenth embodiments.

Twenty Fourth Embodiment

A twenty fourth embodiment of implementation of the present inventionwill be described hereinafter in connection with FIGS. 41 and 42.Herein, the same members as mentioned in the sixteenth to twenty thirdembodiments will be given the same reference numerals and signs andtheir description will be omitted.

FIG. 41 is a plan view illustrating an encoder 460 in the twenty fourthembodiment of implementation of the present invention. The encoder 460is used instead of the encoder 410 of FIG. 24. Configurations other thanthe encoder 460 are as shown in FIG. 24.

FIG. 42 is a partly enlarged perspective view of the encoder 460. Theencoder 460 has an annular shape having a constant radial width. Theencoder 460 has a flat encoder mounting member grounding surface 460 band sensor-opposing surfaces 460 a which increase in the thickness Lfrom the encoder mounting member at a predetermined ratio. The encoder460 is fixed to the encoder mounting member 411 at the encoder mountingmember grounding surface 460 b. The normal direction of the encodermounting member grounding surface 460 b is parallel to the axialdirection. The sensor-opposing surface 460 a of the encoder 460 isdisposed axially opposed to the sensor 420, which is a displacementsensor.

The thickness L of the encoder 460 increases at a predetermined ratio asthe angle increases along the circumferential direction from thereference position. The position at which the thickness L is at maximumand the position at which the thickness L is at minimum are separated bya step. In the present embodiment, the encoder is disposed in sucharrangement that the thickness L gradually increases counterclockwise asviewed from the sensor. Accordingly, the distance between the encoder460 and the sensor 420 changes according to the shape of thesensor-opposing surface 465 a with the rotation of the shaft 402. Thedistance between the encoder 460 and the sensor 420 is stored in acontrol circuit which is not shown according to the angle. Moreover, thecontrol circuit stores the position of the various sensor-opposingsurfaces 460 a and the absolute angle of the shaft 402 in associationwith each other.

The output signal detected by the sensor 420 is as shown in FIG. 38. Themethod of calculating the rotary speed, direction of rotation andabsolute angle is as explained in the twenty second embodiment.

As mentioned above, in accordance with the present embodiment, theencoder 460 and the sensor 420 are disposed axially opposed to eachother. Further, the encoder 460 has a sensor-opposing surface 460 aformed thereon such that the distance from the sensor 420 graduallyincreases or decreases. The sensor 420 outputs output signal accordingto the distance from the sensor-opposing surface 460 a to the controlcircuit. The control circuit analyzes this output signal to detect thespeed, direction and angle of rotation of the shaft 402. Accordingly,the single sensor 420 can be used to detect the speed, direction andangle of rotation of the shaft 402 at the same time, making it possibleto exert the same effect as in the eleventh embodiment.

Twenty Fifth Embodiment

A twenty fifth embodiment of implementation of the present inventionwill be described hereinafter in connection with FIG. 43. Herein, thesame members as mentioned in the sixteenth to twenty third embodimentswill be given the same reference numerals and signs and theirdescription will be omitted.

FIG. 43 is a partly enlarged perspective view illustrating the encoder465 in the twenty fifth embodiment of implementation of the presentinvention. The encoder 465 is used instead of the encoder 410 of FIG.24. Configurations other than the encoder 465 are as shown in FIG. 24.

The encoder 465 has an annular shape having a constant radial width. Theencoder 465 has a flat encoder mounting member grounding surface 465 band sensor-opposing surfaces 465 a which increase in the thickness Lfrom the encoder mounting member at a predetermined ratio. The encoder465 is fixed to the encoder mounting member 411 at the encoder mountingmember grounding surface 465 b. The normal direction of the encodermounting member grounding surface 465 b is parallel to the axialdirection. The sensor-opposing surface 465 a of the encoder 465 isdisposed axially opposed to the sensor 425, which is a magnetism sensor.

The radius L of the encoder 465 increases at a predetermined ratio asthe angle increases along the circumferential direction from thereference position. The position at which the thickness L is at maximumand the position at which the thickness L is at minimum are separated bya step. In the present embodiment, the encoder is disposed in sucharrangement that the thickness L gradually increases counterclockwise asviewed from the sensor. Accordingly, the distance between the encoder465 and the sensor 425 changes according to the shape of thesensor-opposing surface 465 a with the rotation of the shaft 402. Thedistance between the encoder 465 and the sensor 425 is stored in acontrol circuit which is not shown according to the angle. Moreover, thecontrol circuit stores the position of the various sensor-opposingsurfaces 465 a and the absolute angle of the shaft 402 in associationwith each other.

On the sensor-opposing surface 465 a of the encoder 465 are disposed aplurality of N poles 437 and S poles 438 arranged alternately at apredetermined interval. The magnetized regions constituting the N pole437 and S pole 438 each have a predetermined magnetic flux density. TheN pole 437 and S pole 438 each form therearound a magnetic field havingan intensity corresponding to the polarity and magnetic flux densitythereof. Accordingly, a magnetic field corresponding to the magneticflux density of N pole 437 and S pole 438 is formed around the encoder465.

The output signal detected by the sensor 425 is as shown in FIG. 40. Themethod of calculating the rotary speed, direction of rotation andabsolute angle is as explained in the twenty third embodiment.

As mentioned above, in accordance with the present embodiment, theencoder 465 and the sensor 425 are disposed axially opposed to eachother. Further, the encoder 465 has a sensor-opposing surface 465 aformed thereon such that the distance from the sensor 425 graduallyincreases or decreases. The sensor 445 outputs output signal accordingto the distance from the sensor-opposing surface 465 a to the controlcircuit. The control circuit analyzes this output signal to detect thespeed, direction and angle of rotation of the shaft 402. Accordingly,the single sensor 425 can be used to detect the speed, direction andangle of rotation of the shaft 402 at the same time, making it possibleto exert the same effect as in the eleventh embodiment.

Twenty Sixth Embodiment

A twenty sixth embodiment of implementation of the present inventionwill be described hereinafter in connection with FIG. 44. Herein, thesame members as mentioned in the sixteenth to twenty fifth embodimentswill be given the same reference numerals and signs and theirdescription will be omitted.

FIG. 44 illustrates a deep groove ball bearing as a rolling device withsensor having a rotation detecting device according to the twenty sixthembodiment of implementation of the present invention incorporatedtherein. In the present embodiment, the outer ring 403 and the innerring 404 of the deep groove ball bearing have a sensor mounting portion403 d and an encoder mounting portion 404 c which axially extend,respectively.

On the axially outer side 4 d of the encoder mounting portion 404 c isdisposed an encoder 470. The encoder 470 is an encoder having a magnetsuch as encoders 435, 436 and 455 described in the twentieth, twentyfirst and twenty third embodiments disposed thereon. The axial side ofthe encoder 470 is opposed to the sensor mounting portion 403 d.

On the other hand, on the end of the axially inner side 403 e of thesensor mounting portion 403 d is provided standing an annular steelsheet 495. An annular seal 490 is supported by the steel sheet 495 toseal the clearance between the sensor mounting portion 403 d and theencoder mounting portion 404 c.

Further, on the axially inner side 403 e of the sensor mounting portion403 d is disposed a sensor mounting member 486. The sensor mountingmember 486 is positioned between the seal ring 408 and the seal 490.

On the sensor mounting member 486 are disposed a temperature measuringdevice 485 and a sensor 480. The sensor 480 is a magnetism sensor whichmeasures the change of magnetic field formed by the encoder 470 or adisplacement sensor which measures the change of distance. The sensor480 is disposed opposed to the encoder 470 and measures the shape of theencoder 470. The sensor 480 detects the rotary speed, rotation directionand absolute angle of rotary body in the same manner as in thetwentieth, twenty first and twenty third embodiments.

The temperature measuring device 485 measures the temperature of thesensor and encoder and the peripheral members and outputs thetemperature data thus measured to a control circuit which is not shown.In the case where the encoder 470 is magnetized by N pole or S pole, themagnetized regions constituting the N pole and S pole change in magneticflux density with temperature change. The control circuit has a table bywhich the change of magnetic flux density with temperature change iscorrected. Further, the control circuit uses this table to correct theoutput value thus detected and detect the rotary speed, rotationdirection and absolute angle of the shaft. In the case where a contacttype thermometer such as thermocouple is used, the temperature of anonrotary member such as sensor is detected, but in the case where anoncontact type thermometer such as infrared radiation thermometer isused, the detection of the temperature of a rotary member such asencoder is made possible.

As mentioned above, in accordance with the present embodiment, outputvalue corrected in the light of temperature change can be used to detectthe rotary speed, rotation direction and absolute angle of the shaft.Accordingly, the encoder 470 can be used without taking into account theworking temperature conditions of the encoder 470, making it possible toapply the present rotary state detecting device to bearing and rollingdevice more widely.

The core gap between the encoder and the sensor changes with thermalexpansion and shrinkage. This core gap change may be corrected on thebasis of signal from the temperature measuring device.

Further, in the present embodiment, the encoder 470 and the sensor 480are sealed by the seal ring 408 and the seal 490. Therefore, theexternal effect can be minimized, making measurement possible at ahigher accuracy.

Accordingly, the speed, direction and angle of rotation of the shaft canbe detected by a simple structure, making it possible to reduce thenumber of parts and hence the part cost. Further, the reduction of thenumber of parts improves assemblability, making it possible to reducethe assembly cost as well.

Further, since only one sensor is required, the space in the bearing canbe saved, making more compact design possible as a whole. Moreover, thereduction of the number of sensors leads to the reduction of the weightof the bearing as well, contributing to the reduction of fuelconsumption if the bearing is used for automobile or the like.

Further, the same rotation detecting device as in the present embodimentcan be applied to a bearing with sensor described in any of the first totenth embodiments.

INDUSTRIAL APPLICABILITY

In accordance with the present invention, a rolling bearing with sensorwhich can maintain a high precision in detection even if any loadpressing the end surface of race is acted thereon can be provided.

Further, in accordance with the present invention, a rolling bearingwith sensor which can have a plurality of sensors incorporated thereinand can have a reduced width can be provided.

Moreover, in accordance with the present invention, a rolling bearingwith sensor which can block external disturbance such as leakage ofmagnetic flux to maintain a high precision in detection can be provided.

Further, in accordance with the present invention, since the distancebetween the encoder and the sensor-opposing surface differs withposition, a rotary state detecting device and a rolling bearing withsensor can be provided which can judge the rotary speed, rotationdirection and absolute angle by a simple configuration by allowing asensor to measure the distance from the encoder. Moreover, in the caseof the present configuration, only one sensor is required, making itpossible to simplify the configuration and hence reduce the device cost.

Further, in accordance with the present invention, a rotary statedetecting device and a rolling bearing with sensor can be provided whichcan detect the rotary speed of a rotary member by using a single sensorto detect peak because a plurality of magnetized regions constitutingthe encoder have different magnetic flux densities. Moreover, bypreviously grasping the disposition pattern of magnetized regions havingdifferent magnetic flux densities, the rotation direction and absoluteangle of a rotary member can be detected at the same time using a singlesensor. Thus, the reduction of the space on a stationary member can bemade by using a simpler structure than in related art. Further, there isno necessity of providing extra sensors, making it possible to detectthe rotary member at a reduced cost.

1. A rolling bearing comprising: an inner ring; an outer ring; a rollingelement rollably disposed between the inner ring and the outer ring; anda plurality of sensors provided on one of the inner ring and outer ring;wherein the plurality of sensors are disposed at the same position alongan axial direction of the one of the inner ring and the outer ring. 2.The rolling bearing as claimed in claim 1, further comprising aplurality of detection members sensible by the plurality of sensors;wherein the detection members are provided on the other of the innerring and outer ring opposed to the sensors at substantially the sameaxial position as the plurality of sensors.
 3. The rolling bearing asclaimed in claim 2, wherein the detection member is an annular materialhaving an outer surface and an inner surface; and both of the outersurface and the inner surface are sensed by any one of the plurality ofsensors.
 4. The rolling bearing as claimed in claim 3, wherein the outersurface and inner surface of the detection member have magnetizedportions having different magnetization patterns formed thereon.
 5. Therolling bearing as claimed in claim 1, wherein the plurality of sensorsare disposed at positions deviated circumferentially from each other. 6.The rolling bearing as claimed in claim 1 further comprising: a sealstructure provided between the plurality of sensors and the rollingelement.
 7. The rolling bearing with sensor as claimed in claim 1,wherein the plurality of sensors include a magnetism sensor, atemperature sensor and a vibration sensor.
 8. A rolling bearingcomprising: an inner ring; an outer ring; a rolling element rollablydisposed between the inner ring and the outer ring; a sensor provided onone of the inner ring and the outer ring; a detection member sensible bythe sensor, the detection member provided on the other of the inner ringand the outer ring radially and opposed to the sensor; and a noiseshield disposed in the vicinity of the sensor and the detection member.9. The rolling bearing as claimed in claim 8, wherein the sensor is amagnetism sensor which senses magnetism generated by the detectionmember.
 10. The rolling bearing as claimed in claim 8, furthercomprising: a first retaining member made of a magnetic material andfixed to the outer ring, the first retaining member retaining one of thesensor and the detection member; and a second retaining member made of amagnetic material fixed to the inner ring, the second retaining memberretaining the other of the sensor and the detection member; wherein thefirst retaining member and the second retaining member act as the noiseshield.
 11. The rolling bearing as claimed in claim 10, wherein at leastone of the first retaining member and the second retaining member has aside wall extending radially on a side of the sensor and the detectionmember opposite to the rolling element; and the first retaining memberand the second retaining member cover the sensor and the detectionmember while having a U-shaped cross section.
 12. The rolling bearing asclaimed in claim 10, further comprising an interposing side wallradially extending and being disposed at a side of the sensor and thedetection member to face the rolling element; wherein the interposingside wall acts as a noise shield.
 13. The rolling bearing as claimed inclaim 8, wherein the first retaining member and the second retainingmember retain the sensor and the detection member with the sensor andthe detection member opposed radially to each other.
 14. A rotary statedetecting device comprising: an encoder mounted on a rotary member whichrotates relative to a stationary member, the encoder including aplurality of magnetized regions arranged in a row; and a sensor mountedon the stationary member and opposed to the encoder, the sensor fordetecting the magnetic force of the plurality of magnetized regions;wherein the plurality of magnetized regions have different magnetic fluxdensities.
 15. The rotary state detecting device as claimed in claim 14,wherein the plurality of magnetized regions includes a plurality ofalternately arranged N and S poles.
 16. The rotary state detectingdevice as claimed in claim 14, wherein the plurality of magnetizedregions on the encoder are formed by N or S pole.
 17. The rotary statedetecting device as claimed in claim 14, wherein the encoder is opposedto the sensor in a direction along an axis of the rotary member.
 18. Therotary state detecting device as claimed in claim 14, wherein theencoder is opposed to the sensor in a direction along a radial directionof the rotary member.
 19. The rotary state detecting device as claimedin claim 14, wherein the plurality of magnetized regions are arranged sothat the magnetic flux density gradually increases or decreases.
 20. Therotary state detecting device as claimed in claim 14, further comprisinga temperature measuring portion for measuring the temperature of thesensor or encoder or peripheral members.
 21. The rotary state detectingdevice as claimed in claim 14, further comprising a seal member forsealing the encoder and the sensor.
 22. A bearing comprising: an innerring; an outer ring; an encoder mounted on one of the outer ring and theinner ring, the encoder including a plurality of magnetized regionsarranged in a row; and a sensor mounted on the other of the outer ringand the inner ring and being opposed to the encoder, the sensor fordetecting a magnetic force of the plurality of magnetized regions;wherein the plurality of magnetized regions have different magnetic fluxdensities with each other.
 23. The bearing as claimed in claim 85,wherein the plurality of magnetized regions include a plurality ofalternately arranged N and S poles.
 24. The bearing as claimed in claim22, wherein the plurality of magnetized regions on the encoder include Nor S pole.
 25. The bearing as claimed in claim 22, wherein the encoderis axially opposed to the sensor.
 26. The bearing as claimed in claim22, wherein the encoder is radially opposed to the sensor.
 27. Thebearing as claimed in claim 22, wherein the plurality of magnetizedregions are arranged so that the magnetic flux density graduallyincreases or decreases.
 28. The bearing as claimed in claim 22, furthercomprising a temperature measuring portion for measuring the temperatureof the sensor or encoder or peripheral members.
 29. The bearing asclaimed in claim 22, further comprising: a seal member for sealing theencoder and the sensor.
 30. A rotary state detecting device comprising:a sensor mounted on a stationary member; and an encoder mounted on arotary member which rotates relative to the stationary member, theencoder including a sensor opposing surface opposing to the sensor;wherein a distance between the sensor opposing surface and the sensorchanges positionally; and the sensor measures a rotary state of therotary member by measuring the change of the distance.
 31. The rotarystate detecting device as claimed in claim 30, wherein the sensoropposing surface includes a plurality of sensor opposing surfaces; andthe distances between the sensor opposing surfaces and the sensor aremutually different with respect to the plurality of sensor opposingsurfaces.
 32. The rotary state detecting device as claimed in claim 31,wherein the encoder has a plurality of magnetized regions arranged in arow and provided on the sensor opposing surfaces, respectively.
 33. Therotary state detecting device as claimed in claim 30, wherein thedistance between the sensor opposing surface and the sensor graduallyincreases or decreases.
 34. The rotary state detecting device as claimedin claim 33, wherein the encoder has a plurality of magnetized regionsarranged in a row and provided on the sensor opposing surfaces.
 35. Therotary state detecting device as claimed in claim 32, wherein theplurality of magnetized regions include a plurality of alternatelyarranged N and S poles.
 36. The rotary state detecting device as claimedin claim 34, wherein the plurality of magnetized regions include aplurality of alternately arranged N and S poles.
 37. The rotary statedetecting device as claimed in claim 30, wherein the encoder is opposedto the sensor in a direction along an axial direction of the rotarymember.
 38. The rotary state detecting device as claimed in claim 30,wherein the encoder is opposed to the sensor in a direction along aradial direction of the rotary member.
 39. The rotary state detectingdevice as claimed in claim 30 further comprising: a temperaturemeasuring portion for measuring the temperature of the sensor or encoderor peripheral members.
 40. The rotary state detecting device as claimedin claim 30, further comprising: a seal member for sealing the encoderand the sensor.
 41. A rolling bearing comprising: an inner ring; anouter ring; a rolling element rollably disposed between the outer ringand the inner ring; a sensor mounted on one of the outer ring and theinner ring; and an encoder mounted on the other of the outer ring andthe inner ring, the encoder including a sensor opposing surface opposedto the sensor; wherein the distance between the sensor opposing surfaceof the encoder and the sensor changes positionally; and the sensormeasures a rotary state of the rotary member by measuring the change ofthe distance.
 42. The rolling bearing as claimed in claim 41, whereinthe sensor opposing surface includes a plurality of sensor opposingsurfaces; and the distances between the sensor opposing surfaces and thesensor are mutually different with respect to the plurality of sensoropposing surfaces.
 43. The rolling bearing as claimed in claim 42,wherein the encoder has a plurality of magnetized regions arranged in arow and provided on the plurality of sensor opposing surfaces,respectively.
 44. The rolling bearing as claimed in claim 41, whereinthe distance between the sensor opposing surface of the encoder and thesensor gradually increases or decreases.
 45. The rolling bearing asclaimed in claim 44, wherein the encoder has a plurality of magnetizedregions arranged in a row and provided on the sensor opposing surface.46. The rolling bearing as claimed in claim 43, wherein the plurality ofmagnetized regions include a plurality of alternately arranged N and Spoles.
 47. The rolling bearing as claimed in claim 45, wherein theplurality of magnetized regions include a plurality of alternatelyarranged N and S poles.
 48. The rolling bearing as claimed claim 41,wherein the encoder is opposed axially to the sensor.
 49. The rollingbearing as claimed in claim 41, wherein the encoder is opposed radiallyto the sensor.
 50. The rolling bearing as claimed in claim 41, furthercomprising a temperature measuring portion for measuring the temperatureof the sensor or encoder or peripheral members.
 51. The rolling bearingas claimed in claim 41, further comprising a seal member for sealing theencoder and the sensor.